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DEPARTMENT OF COMMERCE AND LABOR 

BUREAU OF FOREIGN AND DOMESTIC COMMERCE 

A. H, BALDWIN, Chief 

SPECIAL AGENTS SERIES—No. 66 


ELECTRICAL 

INSTRUMENTS AND METERS 



WASHINGTON 

GOVERNMENT PRINTING OFFICE s 
1913 




















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CONTENTS. 


Page. 


Letter of submittal. 5 

Introduction. 7 

England: v 

British Thomson-Houston Co. (Ltd.). 7 

Cambridge Scientific Instrument Co. 9 

Edison & Swan Electric Light Co. (Ltd.). 11 

Electrical Apparatus Co. (Ltd ).. 13 

Elliott Bros. 14 

Everett, Edgcumbe & Co. (Ltd.). 20 

Evershed & Vignoles (Ltd.). 26 

Ferranti (Ltd.). 30 

Nalder Bros. & Thompson (Ltd.).y.. 34 

Robert W. Paul. 39 

H. Tinsley & Co. 46 

France: 

J. Carpentier. 49 

Compagnie Anonyme Continental pour la Fabrication des Compteurs.... 50 

Compagnie de Construction Electrique. 53 

Compagnie FAC. 55 

Compagnie pour la Fabrication des Compteurs et Materiel d’Usines a Gaz.. 57 

Maison Graindorge... 66 

Jules Richard. 66 

Germany: 

Allgemeine Elektricitats-Gessellschaft. 68 

Fussner & Fordermann. 71 

S. Guggenheimer. 71 

Hartmann & Braun A. G. 72 

R. Kiesewetter. 76 

Land und Seekabelwerke A. G. 77 

Siemens & Halske A. G. 77 

Siemens-Schuckert Werke. 80 

Vereinigte Elektrotechnische Institute. 82 

Italy: 

C. G. S. Electrical Instrument Co.*. 83 

Compagnia Anonima Continentale gia J. Brunt & C. 85 

Societa Anonyme Siry, Chamon & C. 86 

Societa Edison per la Fabbricazione di Macchine et Apparecchi Elettrici.. 87 

Additional notes. 87 


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LETTER OF SUBMITTAL. 


Department of Commerce and Labor, 

Bureau of Foreign and Domestic Commerce, 

Washington, December 20, 1912. 

Sir: I have the honor to submit herewith a series of reports by 
Commercial Agent H. B. Brooks dealing with the manufacture of 
electrical instruments and meters in Europe. The works of 31 lead¬ 
ing firms are described, attention being paid to equipment, number 
of employees, and hours of labor, and especially to the nature of the 
products manufactured. 

Respectfully, A. H. Baldwin, 

Chief of Bureau. 

To Hon. Charles Nagel, 

Secretary of Commerce and Labor. 



























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• ELECTRICAL INSTRUMENTS AND METERS IN 

EUROPE. 


INTRODUCTION. 

With the ever-increasing use of electricity in almost every branch 
of industry, the manufacture of electrical instruments and meters is 
becoming an important and highly specialized industry in which 
many complex problems arise. In view of the pioneer work in elec¬ 
trical measurements done in Europe, a visit was made to the princi¬ 
pal European manufacturers to obtain such information in regard to 
their organization, methods, and products as would be of interest to 
American makers and users. 

In presenting the following reports the writer wishes to acknowl¬ 
edge his obligations to the leading men in the electrical instrument 
and meter business in Europe, who have permitted inspection of their 
factories and placed interesting and valuable information at his 
disposal. 

ENGLAND. 

BRITISH THOMSON-HOUSTON CO. (LTD.). 

The British Thomson-Houston Co. (Ltd.) is an English electrical 
manufacturing company affiliated with the General Electric Co. of 
Schenectady. Its works are located at Rugby, about 80 miles north¬ 
west of London. Its products cover a wide range, including dynamos, 
motors, steam turbines, electric-railway equipment, switchboards, 
control apparatus, electric lamps, electric-heating apparatus, etc. 

The manufacture of meters is carried on in buildings used for other 
classes of work also, so that no description of buildings will be 
attempted here beyond the statement that they are of brick, several 
stories in height, and well constructed. 

While English machine tools are given the preference, a number 
of American machines are used where they are better adapted for 
the work. Included in the latter are Garvin tapping machines, 
Bardin-Oliver turret lathes, and Brown & Sharpe special tools and 
automatics for small work. The machines are arranged with each 
type in banks, in some cases group driven by electric motors, indi¬ 
vidual motor drive being used where possible. 

About 450 employees are engaged in the instrument and meter work, 
80 per.cent being females. These latter are employed chiefly on 
small assembly work. The working week consists of 52 hours. 

SWITCHBOARD WATT-HOUR METERS. 

The Thomson “ integrating wattmeter ” is made for switchboard 
service in sizes from 5 amperes to 10,000 amperes, two-wire, and from 
50 to 3,000 amperes, three-wire. Above 500 amperes, the two-wire 

7 



8 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

meter is always of the astatic type. The commutator and brushes are 
of silver, and copper is still used for the drag disk. The two-wire 
meter of capacities from 600 amperes up has some interesting points 
of construction. The field coil (for currents from 600 to 1,200 am¬ 
peres) is made up of copper strips in D shape, with the straight side 
at the bottom, and is electrically one turn. Two armatures are ar¬ 
ranged on one shaft; one rotates within the D, the other below the 
flat side of the D. Instead of the familiar 8 or 12 part commutator, 
2-part commutators are used, and each armature is electrically one 
coil. To make the torque more nearly uniform over a revolution, the 
planes of the coils of the two armatures are at right angles; to increase 
the torque, a number of soft-iron disks are placed within the coils. 

From 1,500 to 10,000 amperes the armature construction is as 
described, and the field “ coil ” consists of a straight copper bar 
bridging the terminal studs; this field construction is familiar to 
meter users in the United States. In all the above-described Thom¬ 
son meters a soft-iron box surrounds the drag magnets. The modifi¬ 
cations of the two-wire meter to adapt it for three-wire service are 
obvious. 

DIRECT-CURRENT HOUSE-SERVICE METERS. 

Thomson meters of the house-service type are made in ranges of 
from 5 amperes to 600 amperes. The dials read in B. O. T. (Board of 
Trade) units. 1 For house service, however, the watt-hour meter is not 
popular in England, the ampere-hour meter being in much greater 
demand. The B. T. H. ampere-hour meter is of the mercury type. 
The current flows through a thin cylindrical copper cup contained 
in a mercury chamber. The cup revolves in a narrow air gap of a 
strong permanent magnet, the design being such as to reduce the air 
gap to the minimum. The magnetic field is at once the driving and 
the braking field. It is stated that the design is such as to render 
unnecessary the use of a compounding coil, and that the meter will 
start to register with a load of one-half of 1 per cent of its rated 
current. These meters are made for rated currents from 3 to 500 
amperes. 

The following data on the type MH mercury meter were furnished 
by the makers: Loss in series circuit at full load, 0.1 watt; drop in 
series circuit at full load, 0.02 volt; full-load torque, 35 millimeter- 
grams ; speed of rotation at full load, about 55 revolutions per minute; 
weight of meter complete, 12.5 pounds. 

The company states that ampere-hour meters, because of their 
simplicity, reliability, and small losses, are now in general use in Eng¬ 
land for direct-current circuits. 

The mercury meter is also made in prepayment type, in 3-ampere 
and 5-ampere ranges. The switch is of the knife-blade type, and 
the prepayment mechanism is of purely mechanical construction. 
Other types of mercury meter are made for switchboard and for 
tramcar service. 

SINGLE-PHASE WATT-HOUR METER. 

The company’s type RH single-phase induction watt-hour meter is 
similar in operating principle and external appearance to the 
type I, made in Lynn by the General Electric Co. The driving 

1 The kilowatt-hour is called in England a “ Board of Trade unit,” or often briefly a 
“ unit” 



ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 9 

element is fastened to the cast-iron base of the meter, and the mov¬ 
ing element, magnets, and dial are attached to a cast frame that is 
screwed to projections on the meter base. The frame can thus be 
readily removed to give access to the coils, and replaced without 
altering the calibration of the meter. 

The following data on the type RH meter were supplied by the 
makers: Loss in potential coil, 1.5 watts; loss in 5-ampere series coil, 
at full load, 0.55 watt; drop in 5-ampere series coil, at full load, 0.3 
volt; full-load torque, all capacities, 50 millimeter-grams; weight 
of moving element, 25 grams; speed of rotation at full load, 35 to 
40 revolutions per minute; weight of complete 5-ampere 110-volt 
meter, 8.5 pounds. Horizontal edgewise indicating instruments are 
made at the Rugby works in practically the same form as at Lynn. 

The company obtains most of its materials from British sources, 
very little being supplied from the United States, sells its product 
largely in England, and exports to countries other than the United 
States and the Continent. 

CAMBRIDGE SCIENTIFIC INSTRUMENT CO. 

The Cambridge Scientific Instrument Co. w T as formed in 1895, 
and erected factory buildings the same year at Cambridge, 
England. The original buildings have side and “lantern” lighting. 
At the time of the writer’s visit (March, 1912) a new building was 
under construction, having the most advanced type of saw-tooth 
roof, with large glass area. The location of the works is very favor¬ 
able as regards freedom from dust and dirt. The new building is 
of brick, one story high, with steel framework for the roof. Two 
rows of cast-iron pillars provide intermediate support for the roof 
framework, on account of the large span. The framework is cov¬ 
ered on the outside with sheathing boards and slate, and on the inside 
with asbestos board. 

In addition to the older one-story machine shops, there are several 
two-story buildings containing the offices, drafting rooms, testing 
rooms, etc. Each department of the works is driven by a separate 
400-volt direct-current motor, current being bought from the local 
supply company at 2 cents per kilowatt hour. 

METHODS AND EQUIPMENT. 

The general process of manufacture is adapted to the special re¬ 
quirements of the company’s business. Instead of producing a 
comparatively small number of instruments in large quantities, it 
produces a large number of types and forms, for any one of which 
the demand is necessarily not very great. To produce apparatus 
economically in lots of 10 to 25 requires careful study of methods. 
New instruments are being added from time to time, hence it is not 
feasible, as a rule, to make and store parts in quantity, though this 
is done in the case of some small detail parts. 

A number of American machine tools are in use, including a Cin¬ 
cinnati universal milling machine, a Walker grinder, and several 
Star lathes. It was stated that while the best American machine 
tools (including such as Brown & Sharpe and Cincinnati Milling 
Machine Co.) are very good, nothing better being made, there is 


10 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

too great a gap in quality between this grade and the next lower 
grade. Often a machine tool was wanted for work not of the highest 
grade, and in trying to get an American machine tool for such work, 
an inferior tool was received, not good enough for the work. It is 
stated that American tool designs generally are well thought out, 
but few firms carry the quality right through. It was further stated 
that there was a great and uncertain delay in the delivery of Ameri¬ 
can machine tools. 

A heavy semiautomatic turret lathe of German manufacture 
(Auerbach & Co., Dresden) is considered one of the most useful 
tools in the equipment. It is especially adapted to the machining of 
moderately heavy instrument parts in lots of 10 to 25. A heavy arm 
pivoted at the back of the lathe can be swung down, bringing a 
chaser against the work. This is especially useful for threading 
large tubing, saving the cost of large and expensive dies. 

A high-speed sensitive drilling machine was required for light 
work and as nothing entirely meeting the requirements could be had 
on the market, the company designed and built two of these machines. 
They are used for drilling holes from inch to \ inch in brass or 
gun metal, the maximum speed being 6,000 revolutions per minute. 
The company also manufactures these machines for the market. 

Broca galvanometers are used in the testing rooms; they are sus¬ 
pended from girders at a height of about 3^ feet above the bench. A 
Nernst lamp projector is attached to the wall some distance below 
the galvanometer, and throws a circular spot of light traversed by the 
image of a vertical cross wire to a plane mirror in front of the gal¬ 
vanometer, whence it is reflected back to the plane mirror, down to 
another plane mirror set at 45 degrees to the vertical. From this 
last mirror the rays pass horizontally to a translucent scale in front 
of the observer. The Broca galvanometer is said to give a sensitivity 
rather higher than that of the Thomson reflecting galvanometer, but 
is very much less affected by stray field. It was stated that the mov¬ 
ing about of milli voltmeters on the bench does not disturb the Broca 
galvanometers. 

Over 130 employees are engaged in the work. Female labor is not 
employed. The working week consists of 534 hours. The company 
states that it has never experienced a strike. 

TEMPERATURE-MEASURING APPARATUS. 

The product of the company includes apparatus for temperature 
measurements, electrical and physical apparatus for laboratory use, 
and a variety of other scientific apparatus. Considerable at¬ 
tention is devoted to the design and construction of apparatus for 
special requirements. Recent instruments of this kind include 
4-meter, 24-meter, and 50-meter comparators, apparatus for the in¬ 
vestigation of mine explosions, and sea-wave recording apparatus. 
The company is sole maker of the Fery radiation pyrometers for 
England and several other countries, and has for years given special 
attention to the manufacture of thermoelectric pyrometers and their 
accessories (indicators and recorders), and also platinum resistance 
thermometers. The “ thread recorder ” used with thermocouples has 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 11 

a suspended coil galvanometer whose pointer is depressed by clock¬ 
work once a minute, pressing an inked thread against a paper chart. 

GALVANOMETERS. 

Recent improvements in Cambridge moving-coil galvanometers 
include the use of specially pure silver wire, narrow coils, and 
gold-plated silver suspensions. The coils are specially treated to 
remove any magnetic impurities. 

The Broca galvanometer is of the type having fixed coils and 
moving magnetic system. The special feature is the form of this 
system, which consists of two steel wires hung vertically close 
together. Each wire has like poles at its ends and a consequent 
pole in the middle. The magnetic system is thus astatic. 

The Einthoven string galvanometer has a single fine wire (or 
silvered glass or quartz fiber) in the intense field of a powerful 
electromagnet having a narrow air gap. When a current flows 
through the “ string,” the latter moves across the field. The motion 
is observed with a microscope, or by projecting the image of the 
string on a screen. The prominent features of this galvanometer 
are its extremely short period (as low as 0.01 second), great sensi¬ 
tivity, and freedom from inductance and capacity. 

The Duddell thermogalvanometer has a loop of silver wire which 
is closed at the bottom by a thermocouple of bismuth and antimony 
and is suspended in the field of a permanent magnet. The current 
to be measured flows through a heating coil placed below the ther¬ 
mocouple. The heat sets up a current in the silver loop and the 
latter is deflected more or less, according to the strength of the current. 
The principle of operation is such that the same deflection is ob¬ 
tained for a given current, either direct or alternating, and regard¬ 
less of the frequency or wave form of the latter. It may be used for 
measuring currents used in wireless telegraphy, and is sensitive 
enough, with a suitable heater, to measure telephonic currents. 

The Duddell oscillograph is made for voltages up to 50,000. In 
addition to the high-frequency type having an electromagnet, a 
simpler form is made with a permanent magnet. This is more suit¬ 
able for high-tension work and in cases where the instrument must be 
frequently moved from place to place. 

Materials are obtained chiefly from England, France, and Ger¬ 
many. Purchases from America are limited mainly to tools. The 
product is marketed in all civilized countries. 

EDISON & SWAN ELECTRIC LIGHT CO. (LTD.). 

The Edison & Swan Electric Light Co. (Ltd.) was formed in 1884 
for the manufacture of incandescent lamps and fittings. The com¬ 
pany’s works are located at Ponders End, Middlesex, north of Lon¬ 
don, and are very extensive. The equipment includes machine tools 
of English, German, and American makes. The company’s product 
is primarily electric-lighting apparatus and supplies, including arc 
and incandescent lamps, switchboards, and wiring devices. In addi¬ 
tion. various patented specialties are made for foreign owners, who 
are required by British law to manufacture articles in England in 
order to maintain their English patent rights. 


12 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


AMMETER SHUNTS WITH TERMINALS CAST ON. 

As a part of its regular product the company makes electrical meas¬ 
uring instruments. The direct-current instruments are of the mov¬ 
ing-coil type. The company uses manganin for ammeter shunts on 
account of its low thermal electromotive force. Most makers con¬ 
struct ammeter shunts by soldering the resistance metal into slots 
cut into the brass or copper terminals. The Edison &-Swan Co. casts 
the terminal around the resistance-metal strips. It is claimed that 
when this is carefully done a joint results that is practically perfect, 
and that such shunts will carry much heavier overloads without dam¬ 
age than will the usual soldered shunts. The standard shunt drop at 
full load is 75 millivolts. The adoption .of this figure is due to the 
influence of the British standard specification for ammeters and 
voltmeters. 

SOFT-IRON INSTRUMENTS-COST INDICATOR. 

Soft-iron instruments are constructed on the repulsion principle, 
with spring control or gravity control. Air damping is used for many 
of the soft-iron instruments, the use of die castings making this pos¬ 
sible without too great expense. Soft-iron ammeters are also made 
as power gauges, the scale being marked in horsepower for some 
particular motor. To do this the customer sends in the test curve or 
data for the motor, and the scale of the ammeter is marked accord¬ 
ingly. The “cost indicator” made by the company is an ammeter 
(either switchboard or portable) whose scale is marked in cost per 
100 hours at some specified rate of charge for electricity. Instruments 
of this kind should be very useful in selling electric lamps, heating 
devices, etc., as the result indicated requires no computation or ex¬ 
planation to the customer, as is necessary when instruments reading in 
electrical units are used. 

CARDEW VOLTMETER-CALIBRATING THE INSTRUMENTS-LABOR. 

The Cardew voltmeter is still listed in the company’s catalogue, 
and it is said that they are still used in some central stations. The 
company also makes portable instruments, both direct current and 
alternating current, in various forms, including portable instruments 
with gravity control, which, so far as the writer is aware, are un¬ 
known in the United States. 

In calibrating the instruments manufactured, the company uses 
secondary standard instruments, both alternating-current and direct- 
current. The alternating-current secondary standards are periodi¬ 
cally checked by comparison with Kelvin balances. These balances 
are sent once a year to the Board of Trade (Government) laboratory 
for certification of correctness. The direct-current secondary stand¬ 
ards are checked by means of a potentiometer. 

The company obtains most of the material used in instrument manu¬ 
facture from English sources, very little American material being 
used. The average wages are about 8 shillings ($1.95) per week for 
girls and 40 shillings ($9.73) per week for men. The ordinary work¬ 
ing week is 49^ hours. The company’s product is marketed prin¬ 
cipally in the United Kingdom, but a considerable portion is exported 
to the colonies and other countries. Very little, if any, is marketed in 
the United States. 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


13 


ELECTRICAL APPARATUS CO. (LTD.). 

The works of the Electrical Apparatus Co. (Ltd.) are located near 
Vauxhall Station, in the southern part of London. The present 
building will accommodate 250 workmen, and the site will permit 
extension of the building to accommodate 200 more. The company 
has practically no American equipment, as it finds the products of 
the English machine-tool makers satisfactory. The equipment is 
very complete, the company making even such standard parts as nuts 
and screws. No American material is used, with the possible excep¬ 
tion of copper. Female labor is employed only in the offices. 

A prominent feature of the company’s work is the manufacture of 
motor starters of original design, including a slow-motion, or “ fool¬ 
proof,” starter, in which a ratchet motion obliges the operator to 
advance the starting lever from the middle of one contact step to the 
middle of the next one, it being impossible to advance more than one 
step at a time. If for any reason it is desirable to throw the lever 
back to the open-circuit position, or if the voltage fails while the 
motor is running, there is no impediment to the free backward move¬ 
ment of the lever. 

THE E. A. C. AMPERE-HOUR METER. 

The product of chief interest is the company’s ampere-hour meter, 
which is designated as the E. A. C. high-torque meter. The general 
form is very similar to that of small induction watt-hour meters 
brought out by several of the leading American makers a year or 
two ago. 

The armature coils, three in number, are wound in “ pancake ” 
form and are inclosed within two thin aluminum disks, with suitable 
insulation. The disks are spun together. The complete armature 
is tested with 500 volts for insulation between shaft and circuit. The 
commutator has three segments of 18-carat gold insulated from 
the steel shaft by a tube of ebonite. The brushes are tipped with 
gold contacts, which make an edgewise contact on the commutator; 
thus a small total pressure of the brush on the commutator gives 
a relatively large pressure per unit of contact surface and tends 
to insure good contact. The lower shaft end, which is not removable, 
is protected by a brass cap. 

The armkture revolves in the field of two strong permanent mag¬ 
nets, which thus supply the working field for the armature coils and 
the retarding field for the drag disk. The winding is such as to 
require about 1 volt drop at full load, the armature current being 
about 0.25 ampere. The armature resistance is thus relatively high, 
and variations of brush contact resistance are said to have a negligible 
effect upon the accuracy. 

NONINDUCTIVE SHUNT-DETAILS OF METER CONSTRUCTION. 

The armature circuit is connected in parallel with an alloy shunt 
of negligible temperature coefficient. At first thought it would 
appear that the inductance of a direct-current shunt was of no con¬ 
sequence. However, it has been found that when a meter with an 
inductive shunt is subjected to a short circuit, the inductance of the 


14 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

shunt tends to increase the relative proportion of current through the 
armature. The 1^ and 2J ampere meters as now constructed have 
the shunt wire reflexed to give a more nearly noninductive shunt. 

Other constructional details of the meter are given as follows: 
Magnets are of tungsten steel; jewels of Ceylon sapphire; mica only 
is used as insulating material. A substantial cast-iron case is used, 
with provision for excluding dust and dampness. The diameter of 
the commutator is given as 0.07 inch; weight of moving element, 45 
grams; full-load speed, about 150 revolutions per minute; full-load 
torque, 200 millimeter grams. 

Meters of the same capacity are tested in series, using indicating 
ammeter and stop watch. Several of the ammeters are of American 
make. The company’s output of meters is about 10,000 per year. 
These are sold chiefly to English central stations. 

ELLIOTT BROS. 

The firm of Elliott Bros., manufacturers of electrical and mechani¬ 
cal instruments, was founded in 1800, and thus has the distinction 
of being the longest established in its line in England, if not in the 
world. In the course of its growth the firm’s business was carried 
on in various locations in London. The buildings at present occupied 
at Lewisham, in the suburbs of London, were completed and entered 
in 1900, and are accordingly called the “ Century Works.” 

The main shop and also the main test room are one-story struc¬ 
tures, each of which is built integral with a two-story portion. The 
one-story construction was employed to provide roof lighting for those 
important parts of the works. The upper floor of the test-room build¬ 
ing contains the offices. The cabinet shop and the group of buildings 
containing the power house, foundry, etc., are one-story buildings. 

AMERICAN METHODS-EQUIPMENT. 

The firm has adopted American methods and uses many American 
tools, including Brown & Sharpe milling machines; grinders of 
American make are also in use. The firm has a high regard for 
American machine tools of the better class, but since the English 
makers have greatly improved their products in recent years it is 
possible to purchase English equipment, which the firm naturally 
prefers to do, other things being equal. Herbert’s milling machines, 
for example, are considered by the firm to be very good, and they can 
usually be bought for less than the high-class American milling 
machines. In the tool room are lathes made by Brown & Sharpe, 
Providence, K. I.; Pratt & Whitney, Hartford, Conn.; and Ludwig 
Loewe & Co., Berlin, Germany; American-made milling machines 
and shapers are also used. 

Group driving is used for most of the machines. A 200-volt direct- 
current motor drives one or several line shafts. The motors are of 
uniform size and machines enough to load each motor are connected 
to it. In the case of a number of small bench lathes the use of indi¬ 
vidual drive has been found both convenient and economical of 
power. Each lathe is driven by a one-fourth horsepower direct- 
current motor mounted on a vertical support from the back of the 
bench; the round driving belt comes down to the lathe at about 45° 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 15 

to the vertical. The motor has a three-step cone pulley to suit the 
cone pulley of the lathe; hence no intermediate shafting or gearing 
is necessary. The motor is started or stopped by a simple switch. 
The arrangement seems to be a very convenient one for light work, 
where frequent stoppages occur. 

The foundry is equipped with coke and gas furnaces, and produces 
all the castings used; these are of copper, brass, gun metal, and alu¬ 
minum. At one time many instrument parts were made by the die- 
casting process, but this has been given up, as later methods have 
been devised by which parts can be produced at equally low cost (in 
some cases at lower cost) on “ capstan ” (turret) lathes. Gas-fired 
ovens are used in the smith’s shop for hardening and tempering; the 
correct temperatures are determined by electrical pyrometer. 

ELECTRICAL ENERGY-CABINET SHOP-PRINTING DEPARTMENT. 

The electrical energy used in the works is purchased from a local 
company, the supply being at 3,000 volts alternating current. This 
is stepped down, and is converted by two 100-kilowatt motor gen¬ 
erators to 200 volts direct current. 

The cabinet shop is equipped with motor-driven machine tools, and 
produces a large amount of high-grade woodwork for instrument 
bases and cases, telegraph apparatus, etc. A great deal of woodwork 
for telegraph and other apparatus intended for use in hot climates 
is made from teak. This wood, which is but little known in the 
United States, is immune from attack by ants. 

A printing department is maintained that not only provides most 
of the regular printing and stationery but is also equipped with three 
special machines for ruling, printing, and punching the long rolls of 
paper used in the Elliott recording instruments. The paper for this 
purpose is bought in large quantities to close specifications as to 
quality, thickness, and width, and is given the special treatment that 
experience has shown to be necessary for the best results. 

LABOR AND WAGES. 

About 450 employees are engaged in the works, only 21 being 
female. The latter are employed only in the offices and in some 
kinds of calibration and testing. The firm’s experience is that boys 
are better for winding coils. Girls are said to do well at light rou¬ 
tine work, but are content to go on year after year doing the same 
kind of work, whereas boys are ambitious and desire to learn as 
many things as possible. A girl may be taught to calibrate 100- 
ampere ammeters, for example, and will do very well on a lot of these, 
but if she is to do such instruments one day, another range the next 
day, and so on, she does not make a success of it and requires too 
much superintendence. The same characteristic makes her unsuitable 
for repair work. The working hours for boys and men in the shops 
are from 7.30 to 12.30 and from 1.30 to 6; work stops at 12.30 on 
Saturdays. Girls begin work at 9 o’clock, but otherwise the hours 
are the same as for the men. 

The piecework system is used for nearly all parts made in quan¬ 
tity. The average instrument maker earns 8 to 9 pence (16 to 18 
cents) per hour. Some of the highest-class men on this work and 


16 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

also the toolmakers earn 10 pence to 1 shilling (20 to 24 cents) an 
hour, and can do better. The firm never cuts the piecework price 
unless the method of production is changed so as to reduce the 
amount of work required. The “ time-limit ” system is used in the 
testing room; thus, if 8 hours is the allotted time for a particular 
piece of work, and a man does it in 6 hours, he gets pay for one of 
the hours saved and the firm saves the other hour. In some English 
electrical works boys are required to work without pay on entering, 
or even to pay a premium for the privilege of working. This is not 
the practice at the works of Elliott Bros.; a boy on entering is paid 
a minimum of 11 pence (2^ cents) per hour; his pay is then raised 
as he acquires skill. 

There are about a dozen labor unions, all independent, among the 
employees, each comprising the men of a particular section of the 
works. Very little trouble has been experienced from strikes. In 
January, 1912, there were 3 men employed who had been w T ith the 
firm continuously for over 40 years, 8 who had been employed over 
30 years, 13 over 20 years, and a large number over 10 years. 

A number of organizations for the welfare of the employees are in 
effect. These are known as the amusements committee, the sick 
club (which pays sick benefits), the loan club, the holiday fund, the 
library, and the orchestra, which last is under the management of the 
amusements committee. In addition, written suggestions for im¬ 
provement of product, methods, etc., are invited from the employees, 
and a suitable return is made for suggestions which can be used. 
These features, it is stated, are due to the example of the National 
Cash Register Co., of Dayton, Ohio. 

MATERIALS—THE FIRM’S PRODUCTS. 

The firm obtains practically all its materials from British sources, 
although some specialties, such as Norton grinding wheels, are 
obtained from America. Aside from the natural desire of the firm 
to use British material, the American maker or dealer usually asks 
higher prices, and the long time required to obtain American supplies 
is a serious drawback. American dealers might compete successfully 
for large orders with a long time for delivery (say, several months). 

The firm’s product covers a wide range. Moving-coil direct-cur- 
rent instruments are made in switchboard and in portable forms; 
alternating-current instruments are made on both the moving-iron 
and the electrodynamometer principle; both alternating-current and 
direct-current recording instruments are made. Current and poten¬ 
tial transformers (switchboard and portable) are made for currents 
up to 10,000 amperes and voltages up to 20,000. Leakage indicators, 
alternating-current and direct-current, are made in switchboard 
form; these instruments are used in England in compliance with the 
Home Office regulations for the supply of electricity in mines. Port¬ 
able testing sets are made consisting of two electrodynamometer 
instruments in a single case. In addition to the more usual combina¬ 
tion of voltmeter and ammeter the following combinations are fur¬ 
nished : Two voltmeters, two ammeters, two wattmeters, voltmeter 
and ammeter, voltmeter and wattmeter, ammeter and wattmeter. 
Triple sets are also made, having any desired combination of three 
of the above units. Other portable sets include a fault-localizing 
bridge, a rail-bond test set, and a photometer. 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


17 


INTERESTING FEATURES OF THE FIRM’S INSTRUMENTS. 

Both the switchboard and portable instruments have window 
openings of liberal size, giving well-lighted scales, and facilitating 
the reading of instruments too high from the floor line. Ammeter 
shunts are electrically interchangeable, as are the millivoltmeters. 
Furthermore, the shunts are mechanically interchangeable, and this 
feature is considered to be worth the cost, although requiring a heavy 
outlay for jigs. Switchboard shunts are made up to 15,000 amperes 
capacity, and the standard drop at full load is 75 millivolts. This 
value is due to the British Standard Specification for Ammeters and 
Voltmeters, Report No. 49 of the Engineering Standards Committee. 

The resistance material used for the switchboard shunts is eureka 
alloy, which is extensively used by the British makers; its properties 
are substantially the same as those of constantan, which is sold in the 
United States under the trade names of “ Advance ” and “ la la.” 
Manganin is used for portable shunts to avoid the thermoelectric 
errors that would be of consequence in the more accurate work for 
which portable instruments are often employed, such as testing con¬ 
sumers’ meters. 

All of the firm’s precision direct-current ammeters are provided 
with a temperature-compensating arrangement devised by A. Camp¬ 
bell (see Journal of the Proceedings of the Institution of Electrical 
Engineers, vol. 35, p. 197). This consists of four coils connected as a 
Wheatstone bridge; two diagonally opposite arms are of manganin 
and the other two are of copper. The two manganin coils are usually 
equal, and the copper coils are equal; the relative values of copper 
and manganin coils are such that the bridge is unbalanced. The 
millivoltmeter is connected as one diagonal of the bridge, and the 
other two corners are connected by leads to the potential terminals 
of the ammeter shunt. This plan is said to give complete temperature 
compensation with a shunt drop equal to three times the copper drop 
in the millivoltmeter. 

Alternating-current instruments on the electrodynamometer prin¬ 
ciple are made with moving coils of aluminum wire, surrounding the 
spherical fixed coil. The use of aluminum wire reduces the moment 
of inertia of the coil very considerably. These instruments have 
permanent magnet damping. 

SHUNTED WATTMETER. 

A novel alternating-current instrument made by the firm is the 
shunted wattmeter, which was produced in order to avoid the con¬ 
structional difficulties encountered in “ straight-through ” wattmeters 
of the usual type for heavy currents, as well as to provide a wattmeter 
■whose current range can be readily changed. A question that will 
arise at once is that of possible error due to the lag of the current in 
the series winding of the wattmeter with respect to the current in 
the shunt. Following is a brief outline of the manner in which this 
question is met: The moving coil is the current coil and surrounds the 
spherical fixed coil, which is wound with relatively fine wire. This 
fixed coil, with a noninductive added resistance of low temperature 
coefficient, forms the potential circuit. The angle of lag in this 

65509°—13-2 


18 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

circuit is somewhat less than the angle of lag of the current in the 
moving coil with respect to the line current; hence the instrument 
is made to read correctly by adding noninductive resistance to the 
moving-coil circuit. The adjustment of this resistance is conven¬ 
iently made by passing the rated current through the shunt from one 
armature of a two-alternator set and applying rated voltage from the 
other armature to the potential circuit. By means of a standard 
wattmeter of the straight-through ” type whose windings are in the 
same circuits any small adjustment is made that is needed to bring 
the current and the voltage into quadrature. The small deflection 
of the shunted wattmeter is then reduced to zero by adjustment of 
the added resistance in series with the moving (current) coil. The 
shunt is made of manganin, while the current-coil circuit is part 
copper and part manganin. With a drop on the shunt at full load of 
about one volt, the proportions of copper and manganin are such as 
to require a temperature correction of about 0.2 per cent per degree 
centigrade. Shunted electrodynamometer ammeters are also made. 

MOVING-IRON AMMETERS-FORMS OF RECORDING INSTRUMENTS. 

Moving-iron ammeters are made on the “ straight-through ” prin¬ 
ciple up to five amperes; above that, five-ampere ammeters are used 
with manganin shunts. This allows the same instrument to be used 
on either alternating or direct current. When only alternating cur¬ 
rent is to be measured, current transformers may be used in place of 
the shunts. Current transformers for switchboard use have the sec¬ 
ondary winding highly insulated, and consequently on high-voltage 
circuits the transformer as a whole must be insulated, usually by 
mounting it on a porcelain insulator, in case the primary line is not 
strong enough to support the weight of the transformer. This is the 
reverse of the usual American practice, which is to provide high 
insulation on the high-voltage coil; since the secondary circuit is 
usually grounded, it is not necessary to insulate it highly from the 
core and case. In constructing potential transformers, the firm fol¬ 
lows the usual practice of highly insulating the primary winding. 

Recording instruments are made in switchboard and portable 
forms. For alternating current an electrodynamometer system is 
used, with an oil dashpot for damping; for direct current the moving- 
coil system is used. The clocks are made by the firm; they are inter¬ 
changeable and can be readily removed from the case, so that a user 
of a number of Elliott recorders can keep a spare clock. An in¬ 
teresting accessory for the recorder is the “ telltale attachment,” 
which is simply a small hole covered by a spring flap, at the side of 
the recorder. A small plunger is provided that will pass through 
the hole and has a rubber initial on the end. This device is intended 
for use when it is desired to have a check on the presence of the 
switchboard attendant, who is required to ink the initial at stated 
intervals and stamp the paper chart. 

RAIL-BOND TEST SET—RESISTANCES. 

A rail-bond test set made by the firm consists of two center-zero 
millivoltmeters mounted in a carrying case. By means of contact 
rods one millivoltmeter is connected across the rail joint, while the 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


19 


other is connected across a portion of the solid rail. By varying the 
position of one of the contact rods both millivoltmeters are made to 
give the same reading; the distance between two of the contact 
points then gives the length of solid rail whose resistance is equal to 
that of the joint. 

The firm makes standard resistances, both laboratory and work¬ 
shop forms, for oil cooling and for air cooling; also plug and dial 
resistance boxes and bridges. Manganin wire and sheet are used, 
though, in common with a number of other English makers, the firm 
considers it a less reliable alloy than platinum-silver or eureka. This 
latter is generally preferred for higher values of resistance, where 
its high thermal electromotive force against copper is not a dis¬ 
advantage. The Elliott five-dial universal shunt is a piece of re¬ 
sistance apparatus intended to have as many uses as possible. It 
may be used as an Ayrton-Mather universal galvanometer shunt, as 
a Wheatstone bridge, a variable rheostat, or a potentiometer. It is 
stated that a submarine-cable station is practically fully equipped 
for testing with one of these instruments and a galvanometer. An 
interesting constructional detail is that the contact studs are faced 
with gold and the levers with platinum. The Elliott potentiometer 
has a dial of 149 equal coils, in series with a slide wire whose resist¬ 
ance is equal to that of one coil of the dial. 

MISCELLANEOUS APPARATUS. 

Other apparatus made by Elliott Bros, includes magnetic testing 
apparatus (the Ewing permeability bridge and the Ewing hysteresis 
tester) and telegraph apparatus, including the Wheatstone apparatus 
for rapid telegraphy and the Baudot printing telegraph. Galvano¬ 
meters are made in many patterns, from the simple detector to the 
elaborate eight-coil high-insulation Thomson; moving-coil galvano¬ 
meters are supplied in a variety of forms. Engineering instruments 
include speed indicators on both mechanical and electrical principles, 
micrometer calipers, steam-engine indicators, and the Wimperis 
accelerometer and gradient measurer. A special precision lathe is 
in use for cutting the screws of the micrometers. The lead screw is 
a very accurate one, and its small errors are prevented from repeating 
themselves in the screws cut by the lathe. To these may be added 
surveying instruments, in the manufacture of which Elliott Bros, 
have had a very long experience. 

The Partridge sparklet fuse made by Elliott Bros, is intended for 
the protection of high-voltage circuits. It contains two “ sparklets ” 
such as are used in aerating liquids. These are placed so that the 
arc that follows the melting of the fuse melts the thin metal of the 
sparklets; the resulting rush of gas blows out the arc. 

The firm makes a large variety of apparatus for use on shipboard, 
of which the most interesting from an electrical standpoint is the 
Anschutz gyro compass. This compass operates on the principle of 
the gyroscope, the rotating portion being part of an induction motor 
operating at 20,000 revolutions per minute. To drive this motor, 
high-frequency currents are supplied from a small motor-generator 
set * on account of the high speed and the large moment of inertia, 
half an hour is required to bring the compass up from rest to full 
speed and it will run several hours after the driving current is 



20 


ELECTKICAL INSTRUMENTS AND METEES IN EUROPE. 


broken. This compass makes possible the use of subsidiary com¬ 
passes about the ship, all of which are under the control of the master 
compass. 

CALIBRATING AND TESTING ELECTRICAL INSTRUMENTS. 

In calibrating and testing electrical instruments use is made of 
“ substandard ” instruments, which are periodically checked by ref¬ 
erence to standards of the best grade. For example, precision direct- 
current instruments are used as substandards, and are periodically 
checked against potentiometers. As standard instruments for alter¬ 
nating-current, electrodynamometer instruments are used whose con¬ 
struction is such as to avoid errors due to eddy currents, skin effect, 
etc. These are checked on direct current. Alternating currents, 
single and polyphase, are obtained from motor generators. Eight 
large storage cells, which can be connected in various groupings, pro¬ 
vide heavy currents for testing large ammeters and shunts. A bat¬ 
tery of 1,000 small storage cells (made in the firm’s works) is used for 
small currents at voltages up to 2,000. 

The products of the Century Works are marketed throughout the 
world, a large part of the production being exported. On account 
of the high tariff only a relatively small amount goes to the United 
States, where sales of late years have been confined principally to 
recording instruments. 

EVERETT, EDGCUMBE & CO. (LTD.). 

The Collindale works of Everett, Edgcumbe & Co. (Ltd.) are 
located at Hendon, one of the northwest suburbs of London. The 
business was founded in 1896 by E. I. Everett, and was carried on in 
several locations in the city of London. In 1900 Kenelm Edgcumbe 
became a member of the firm. The city quarters becoming succes¬ 
sively inadequate, it was decided to build a factory in the suburbs, 
in order to secure more space and also better light and air and free¬ 
dom from dust. A site of 1J acres was secured, and the buildings 
were designed and built by the firm. They were completed and 
manufacturing was begun in 1905. 

BUILDINGS AND EQUIPMENT. 

The principal buildings are of brick, two stories high. Although 
the weaving-shed roof was not used, the roof contains sufficient glass 
to give good lighting. The main building contains the machine 
shop on the ground floor; the upper floor contains the stores of 
finished parts and movements, and accommodates the work of wind¬ 
ing, assembling, and testing. The office building contains the general 
offices on the first floor; the upper floor contains the cost department, 
the drafting room, and the experimental laboratory. The power 
plant is housed in a smaller building; it consists of a gas engine 
driving a direct-current generator, with a motor generator connected 
to the town mains as a reserve unit. The current generated in this 
plant is used for lighting, testing, and charging storage batteries. 
A gas engine drives the machine shop by line shafting. Both en¬ 
gines are operated by suction gas, and a fan is used to transmit some 
of the gas to another building, where it is used to heat plating baths 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 21 

and enameling ovens. Another building is devoted to woodworking, 
and is equipped with power machines. 

In the equipment of the machine shop American makers are fairly 
well represented. Brown & Sharpe Manufacturing Co., Cincinnati 
Milling Machine Co., and Garvin Machine Co. milling machines, and 
W. F. & J. Barnes Co. and Hoefler drills are in use, as well as a lathe, 
a power hack saw, a punch press, and many small tools of American 
manufacture. 

DIE CASTINGS—AIR-DAMPING BOXES. 

The reduction of manufacturing costs is a very urgent problem 
with the English instrument maker. Everett, Edgcumbe & Co. have 
studied this problem with good results. They use die castings 
largely, and having in mind the trouble caused by the use of certain 
unstable aluminum alloys for this purpose, they use a mixture which 
contains none of the treacherous metal, zinc, whose presence in some 
alloys is liable to cause deterioration. The spools of moving-iron 
instruments are die cast. The air-damping boxes with which many 1 
of the firm’s instruments are fitted are not made of die castings, as 
might be supposed, but are stamped from sheet brass in halves, which 
are then soldered together. 

MILLING POLE PIECES-COIL-WINDING MACHINE. 

An interesting machine which effects economy in machining cast- 
iron pole pieces is a double milling machine, having face cutters with 
inserted teeth. The two cutters face each other, one being carried by 
the spindle of a fixed head, the other by the spindle of a head which 
can be made to move toward or from the fixed head, so as to vary 
the distance between the milled surfaces. This movable head has a 
micrometer adjustment, and can be clamped to the bed when the 
desired distance is obtained. 

For winding finer sizes of wire, as used in voltmeter coils, resist¬ 
ance spools, etc., special machines are used. These have a carriage 
for guiding the wire as it winds onto the bobbin, the carriage con¬ 
taining a half nut which rests on a feed screw and can be lifted off if 
desired. The feed-screw shaft carries two clutch pulleys which are 
revolved in opposite directions by a single round belt which is driven 
by a pulley on the head spindle carrying the bobbin to be wound; 
by exchanging this latter pulley for others of different sizes the 
pitch can be varied to suit various diameters of wire. The belt passes 
down from one clutch pulley, through a hole in the bench, then over 
a weighted pulley 2 and back over the other clutch pulley. This 
weighted pulley not only enables a single driving belt to run the two 
clutch pulleys in opposite directions, but also automatically keeps the 
right tension on the belt, and permits changes of size of the driving 
pulley without change of belt tension. The machine is belt-driven 
by a one-fourth horsepower motor under the bench, which is started 
and stopped by a single switch. The coil to be wound is carried in 
any suitable way on the head spindle, and a movable tail stock is pro- 


i This includes all instruments except those of the moving-coil type (which are in¬ 
herently aperiodic), including “motor gauges.” An instrument with no damping is 
almost worthless on fluctuating loads, and it is to be hoped that makers everywhere will 
endeavor to produce damped instruments at prices low enough to make the undamped 


instrument disappear. 

2 As used in telephone 


switchboards to take up the slack in the cords. 




22 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


vicled to support the outer end of long bobbins or resistance cards. 
A very simple and effective counter is provided for indicating the 
number of turns of wire wound. This consists of two 100-tooth 
wheels made of heavy sheet brass; one is driven by a worm on the 
head spindle, and carries a 10-tooth pinion which drives the second 
wheel. These wheels are carried on vertical studs projecting up from 
the frame. An index which extends to the circumference is then 
slipped on to each stud, friction tight. The wheels are marked with 
100 divisions each, and thus count up to 1,000 turns. The indexes 
may be turned to any desired position to read zero for the next coil 
to be wound, and, if desired, the indexes may be slipped up the 
spindle and the gears raised so as to be out of mesh with each other 
and the worm, when they may be turned to any desired position and 
again brought into mesh. 

METHOD OF MAKING INSTRUMENT SCALES. 

All scales are made to fit the particular instrument, no law being 
assumed for a type and no printed or engraved scales being used. 
When an instrument is ready for calibration a uniformly divided 
scale is put in it, and readings are taken on this scale for various 
values of current, voltage, or other quantity concerned, and corre¬ 
sponding readings are taken on a working standard instrument. 1 2 
These readings are given to the operator of a special scale-dividing 
machine, by means of which a scale may be quickly made to suit the 
particular instrument. The operation of this machine is simple and 
rapid, and makes it possible to locate every mark on the scale where 
it should be.* 

In addition, a number of special machines are in use for printing 
the figures on instrument scales and recorder charts. These machines 
were designed by E. I. Everett, to whom the w r riter is indebted for 
the opportunity to see them and to give the above description of the 
winding machine. 

EQUIPMENT FOR TESTING-LABOR CONDITIONS. 

An equipment of large storage cells provides heavy current at low 
voltage for ammeter testing, and a large number of small cells pro¬ 
vide for voltmeter testing. To supply alternating currents, small 
motor generators are located in the testing room. One of these con¬ 
sists of a direct-current motor driving two alternators through clamp 
couplings. One alternator may be used to supply the current coil of 
a wattmeter or power-factor indicator, the other supplying the volt¬ 
age. By shifting one of the couplings any desired phase relation 
between the current and the voltage may be obtained. 

Special attention is given by the firm to the matter of adequate 
insulation of its instruments. Before being sent out each instrument 
is given an insulation test of from 1,500 to 2,000 volts. This applies 
to all instruments irrespective of price or type. 


1 These are in turn checked by laboratory standards; for example, direct-current volt¬ 
meters used as working standards are periodically tested by reference to a potentiometer 

2 Some makers locate every tenth mark by test, and consider it sufficient to divide each 
space into 10 equal parts. For moving-coil instruments this no doubt answers very 
well, but in alternating-current instruments whose scales vary a great deal in length of 
a division in different parts, this method is poor, as may be seen on a scale made in this 
way, by comparing the length of certain adjacent spaces, say the one from the ninth 
division line to the tenth with the one from the tenth to the eleventh. 



ELECTRICAL INSTRLTMENTS AND METERS IN EUROPE. 23 

About 25 per cent of the employees are girls, who assemble the 
working parts of instruments, apply enamel to cases, wind coils, ad¬ 
just the simpler kinds of instruments, do routine calibrating, and 
make the scales. The working week consists of 50 hours. The firm 
states that some labor unions exist among the employees, but that no 
trouble from strikes has been experienced. The comfort of the em¬ 
ployees has been looked after; the buildings are evenly heated by the 
hot-water system, 1 and have plenty of light; mess rooms are pro¬ 
vided, one for men and boys, another for the girls. Meals are supplied 
to the employees at reasonable prices. 


OUTLINE OF PRODUCTS-MOVING-COIL INSTRUMENTS. 

The products of Everett, Edgcumbe & Co., while limited almost 
exclusively to technical instruments, cover a wide range. Moving- 
coil, moving-iron, and electrodynamometer principles are used in 
switchboard and portable forms, and electrostatic instruments are 
supplied as switchboard voltmeters and as leakage indicators, or 
u ground detectors ” as they are called in the United States. Record¬ 
ing instruments are made with disk charts and with roll charts, in 
which an ink line is drawn; an inkless recorder is also made. 

The moving-coil instruments differ from the usual examples of 
this type in that a single control spring is used. This spring does 
not conduct current, as this is accomplished by two very flexible 
ligaments at the end of the coil opposite the one carrying the spring. 2 
These ligaments are protected from injury by a heavy block of molded 
insulating material to which the magnet system is attached and which 
supports the system in the metal case. The jewel screws are carried 
by the central iron core, the pivots being on the inside of the coil 
frame and mechanically attached to it, avoiding the use of cement. 
The magnets are artificially aged, and as the decay of permanent 
magnets is thought of by some users as dependent, to some extent 
at least, on the passage of time, the following quotation from the 
firm’s catalogue is of interest: “These three physical effects [varia¬ 
tions in temperature, external magnetizing forces, and mechanical 
vibration] are the only ones which affect the permanency of a modern 
high-class closed-circuit magnet. Passage of time has, in itself, no 
effect on the magnetism.” A compensating moving-coil voltmeter is 
made which indicates the voltage at the distant end of a feeder with¬ 
out the use of pilot wires. 3 


1 The merits of this system seem to be imperfectly appreciated in England, where the 
wasteful open fire, with the resulting smoke nuisance and great inequality of heating, is 
still generally used. 

2 This construction was tried some years ago in the United States, thin silver liga¬ 

ments being used. These were subject to deterioration, which was most probably due to 
the action of free sulphur in the soft rubber tubing used to protect connecting wires within 
the instrument case. Everett, Edgcumbe & Co. use no rubber tubing for this purpose, 
and state that no trouble has occurred due to failure of the ligaments. The use of 
braided sleeving instead of rubber tubing for protecting connecting wires in instruments 
is now common in the better class of switchboard and portable instruments made in the 
United States. , . • . 

3 An instrument for this purpose was constructed by the writer in 1893, in which a 

single moving system was used, wound with fine wire as for an ordinary voltmeter, and 
with coarse wire (as for a millivoltmeter) over the fine wire. Two springs and two fine 
wire helices were used to lead the two currents in and out. The fine wire, in series with 
a suitable high resistance, was connected across the bus bars, and the coarse winding was 
connected to a shunt, or to potential points at the proper distance apart on one of the 
feeder conductors. See Electrical World, vol. 49, p. 1317 ; 1907. For another method of 
accomplishing the same result, see paper by F. E. Haskell, Electrical World, vol. 49, p. 
1031 ; 1907. 




24 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

MOVING-IRON INSTRUMENTS. 

Moving-iron instruments are made on the repulsion principle, and 
also in two forms on the plunger principle; each of the three is 
used where it is best adapted, taking into consideration questions of 
cost, accuracy required, and whether a given instrument is for use on 
alternating current only or on both alternating and direct currents. 
Gravity control is used for some lines of switchboard moving-iron 
instruments, and spring control for others. All these have air damp¬ 
ing. In addition to a legible scale and liberal window openings, 
the firm’s switchboard instruments have cases which are commend¬ 
able because neat and free from superfluous lettering and ornamenta¬ 
tion, which tends to distract attention from the scale itself. 

One type of moving-iron instrument, which the firm calls the 
“ Universal,” is supplied for use on either alternating or direct cur¬ 
rent, without change of calibration, in both switchboard and port¬ 
able forms. Portable ammeters of this type are supplied for use 
in connection with a set of shunts, the range of the instrument alone 
being 1 to 15 amperes. To cut down the temperature correction, 
some extra resistance (“swamp”) is used in series with the copper 
coil, the extra resistance having a negligible temperature coefficient. 
The drop on the shunts at full load is about 185 millivolts. 

The firm constructs water-tight moving-iron ammeters and volt¬ 
meters for use where conditions are severe, as in mines or on ship¬ 
board. The cases are of cast iron for ordinary uses, bronze for 
shipboard, and have two distinct compartments. One of these con¬ 
tains the actuating coil and the terminals; the cables enter this com¬ 
partment through glands. The other compartment contains the 
moving parts and the scale. Both compartments are made water¬ 
tight by the use of asbestos packing under the covers. Each instru¬ 
ment is tested by immersion in water at a depth of 4 feet; no sign 
of moisture in the case must appear. The type of movement is such 
that the same instrument may be used on direct or on alternating 
current, and the design is said to be so liberal that overloads of 200 
or 300 per cent are withstood without injury. 

ELECTRODYNAMOMETER AND ELECTROSTATIC INSTRUMENTS. 

The electrodynamometer principle is used by the firm in construct¬ 
ing switchboard ammeters, voltmeters, and wattmeters. Where such 
instruments are to be used in locations subject to strong and variable 
stray magnetic fields, an astatic movement is supplied on request. 
In addition to wattmeters of standard switchboard grade, an “ in¬ 
dustrial ” wattmeter is also made, which is furnished at a price lower 
than that of the corresponding range of regular switchboard 
wattmeter. 

Electrostatic voltmeters of the suspension type are made by the 
firm for maximum voltages of 130 up to 1,500." From 2,000 to 6,000 
volts, the round pattern pivoted construction is used. For extra 
high voltages (maximum scale reading of 30,000 to 200,000 volts) 
a special type is made. 

INDUCTION INSTRUMENTS-THE “ PALLER.” 

Induction ammeters and voltmeters are made by the firm in round 
pattern, for switchboard use only. Other alternating-current in- 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


25 


struments include power-factor indicators, single and polyphase, 
switchboard and portable forms; frequency meters on the vibrating- 
reed principle, and a rotary synchronizer. In connection with the 
latter, an alternating-current paralleling voltmeter is supplied, called 
the u paller.” The various difficulties that would be encountered in 
attempting to subtract electrically the voltages of the bus bars and 
incoming machine, using a single voltmeter to read the difference, 
are avoided by using two mechanically coupled voltmeter movements, 
each working at the normal current and position of moving element 
(and hence with normal sensitiveness to small changes of voltage), 
and subtracting their torques mechanically. 

GROUND DETECTORS-GRAPHIC INSTRUMENTS. 

Leakage indicators, or ground detectors, are made for central sta¬ 
tion and mine use. For voltages from 2,000 up the electrostatic prin¬ 
ciple is used; for low voltages the moving-coil and moving-iron sys¬ 
tems are used. 

The line of graphic 1 instruments made by the firm includes round 
disk-chart pattern, made as ammeters and voltmeters, in both astatic 
moving-iron type and moving-coil type; pen pattern, for roll charts, 
and also the “ inkless synchronized ” pattern for roll charts, both made 
in moving-coil and also in astatic moving-iron types. In the inkless 
pattern the index is ordinarily free from the chart, and hence ready 
to take up its proper position without friction. In place of the usual 
pen the index has a steel stylus. At intervals of five seconds an elec¬ 
tric circuit through a solenoid in the graphic instrument is closed by 
a master clock, and the stylus is pressed against a typewriter ribbon, 
thus making a dot on the chart. This makes a practically continuous 
line, unless the quantity to be measured is changing rapidly, in which 
case more frequent depressions of the stylus can be arranged for. The 
inkless synchronized pattern is especially adapted for use in graphic 
power-factor meters, since the forces acting are relatively small, and 
pen friction would cause serious errors. Combined graphic instru¬ 
ments are made to record two quantities on the same chart; for ex¬ 
ample, the volts and amperes on a particular circuit. 

RESISTANCE APP AR ATUS-POTENTIOMETERS. 

The firm makes a line of resistance-measuring apparatus under the 
name of “ Everight ” ohmmeters. These operate on the 'Wlieatstone- 
bridge principle, with a single circular slide resistance having an 
index moving over a graduated scale. Ratio coils provide for several 
ranges, and a portable galvanometer is built in. These ohmmeters 
are made in four patterns, the first being provided with a hand 
magneto generator for various voltages from 100 to 1,000, the corre¬ 
sponding upper limit of measurement being 20 megohms to 1,000 
megohms, with a lower limit of 10,000 ohms in all cases. The next 
instrument of the series is operated by a battery, either self-contained 
or separate, which gives from 3 to 4 volts; the ratio coils are 5 in 

1 The following, from the firm’s catalogue, is worth quoting at this point: “ Owing to 
the word ‘ recording ’ being applied both to instruments which record on a chart and also 
to instruments which record on a train of dials, we have, in order to avoid confusion, de¬ 
scribed the former as ‘ graphic ’ instruments and the latter as ‘integrating ’ instru¬ 
ments, and we think that the difficulties may possibly disappear.” 



26 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


number, and the total range of measurement is from 0.1 ohm to 11,000 
ohms. The third instrument combines the ranges of the two pre¬ 
ceding; the fourth is constructed on a modification of the Kelvin 
double-bridge principle, and has a range of 0.001 to 1 ohm. 

The Everett-Edgcumbe portable potentiometer is intended espe¬ 
cially for factory and central-station use. Electrically, it consists of 
14 equal coils, with a slide wire whose resistance is equal to that of 
one coil. The regulating rheostat, galvanometer, and standard cell 
are built in, the whole outfit being compact (11 by 7 by 9 inches). 

PHOTOMETRIC AND MISCELLANEOUS APPARATUS. 

Photometric apparatus made by the firm includes a standard pho¬ 
tometer bench, with rotating lamp holders and other accessories; a 
workshop photometer at a very moderate price ($7.29) and three 
forms of portable photometer. 

In the line of electric traction accessories the firm makes several 
specialties. One of these is a leakage indicator for trolley stand¬ 
ards, which gives an audible signal in case a contact occurs between 
the trolley standard and the wire carried by it. The “ overhead 
equipment tester ” is an attachment to be clamped to the trolley pole, 
two light steel springs being carried in such position as to make con¬ 
tact with the span wire on each side of the trolley wire. A special 
moving-coil instrument and switches are connected to the springs and 
to ground through the trucks. With this equipment in place, defec¬ 
tive insulators 1 can be located while the car is traveling at regular 
speed. 

The tramway speed indicator is a combination of magneto gener¬ 
ator belt-driven from- the car axle, and a moving-coil voltmeter, 
marked to read miles per hour, at each end of the car. The rail-bond 
tester is constructed on a principle similar to that used in the firm’s 
ohmmeters above described. Under the head of electric control 
apparatus may be mentioned protective relays for alternating-cur¬ 
rent circuits, to the design of which Mr. Edgcumbe 2 has given special 
attention. 

The firm draws its supplies of material principally from English 
sources. It has so far made no attempt to market its product in the 
United States, chiefly on account of the high tariff. 

EVERSHED & VIGNOLES (LTD.). 

The Acton Lane works of Evershed & Vignoles (Ltd.) are located 
in Chiswick, a residential suburb of London. The present buildings 
were erected in 1903 and were up to the best practice at that time. 
The main workshop is a substantial one-story brick building with a 
saw-tooth roof having the glass to the north. 

The arrangement of the machine tools is such that the raw material 
is received at one end of the shop, where the larger milling machines, 
presses, lathes, etc., are located. After receiving the heavier opera¬ 
tions the material is passed to the middle for operations that can be 
performed with lighter lathes and drills. The parts pass finally to 


1 The Board of Trade regulations require each separate insulator to be tested not less 
frequently than once a month ; defective insulators to be replaced at once 

2 K. Edgcumbe, Electrical Review (London), vol. 69, pp. 126, 163, 233; July 28 Aug 
4 and 11, 1911. 



ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 27 

the farther end of the shop for more delicate work and for final ad¬ 
justment at the benches. Many of the vertical milling machines are 
of American manufacture (Becker) and are well liked by the firm. 
Pratt & Whitney turret lathes are also in use. 

MAIN BUILDING-CARD SYSTEM. 

The main building is a two-storv brick structure adjoining the 
main workshop. It contains the stores, adjusting rooms, and wind¬ 
ing room. The arrangement of the stores is a very convenient one 
and is the outcome of careful study of this important feature of 
manufacture. Each rack or bin has a receptacle for a number of 
cards, upon which entries are made of materials or parts placed in the 
bin and of quantities removed, with the shop order number. Thus at 
any time the balance as shown on the card gives the amount of ma¬ 
terial wffiich should be in the bin. At inventory time the cards are 
taken to the office for stock taking. A further feature of this card 
record is the color scheme, one color denoting raw material, another 
finished parts, etc. 

Adjoining the main building is a calibrating room, with battery 
house. Large storage cells provide currents up to 8,000 amperes for 
testing heavy shunts; smaller cells provide the steady voltage neces¬ 
sary for voltmeter testing. 

THE POWER PLANT-LABOR AND MATERIALS. 

The power plant is located in a separate building. Formerly the 
dynamos were driven by two gas engines supplied with town gas. In 
December, 1911, a large oil engine was installed in place of one of the 
gas engines. The oil engine will hereafter do the work and the gas 
engine will be held in reserve. The offices, drafting, and design 
departments are in a separate building. 

The company has about 300 employees, of whom about 50 are girls 
employed in the winding room. Under normal conditions 50 hours 
constitute a week’s work. The average employee receives about 1 
shilling (24.3 cents) an hour. The men are organized, but the com¬ 
pany has not suffered from strikes or other evidences of discontent 
among the workers. The company draws its supplies of material 
from English sources, and a member of the firm expressed the opinion 
that the American producer could not compete with English sources 
of supply under present conditions. 

SPECIAL PRODUCTS. 

The company’s principal product at one time consisted of indicat¬ 
ing electrical instruments, such as ammeters, voltmeters, etc. While 
these are still manufactured, in recent years this line has been rather 
overshadowed by two somewhat special lines, in connection with 
which the company has secured an international market and repu¬ 
tation. The first includes ships’ telegraphs, stoking indicators for 
use in ships’ boiler rooms, and turret danger signals for giving warn¬ 
ing to ships’ gunners when the fire from the guns of their turrets 
would endanger other turrets or the muzzles of other guns. The lim¬ 
itations of the present article allow of only this reference to these 


28 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


interesting instruments, which have been worked out with great skill 
to secure the reliability so vital in such apparatus, which must work 
under unfavorable conditions of shock, exposure to sea air, etc. The 
other special line is that of direct-reading portable apparatus for the 
measurement of resistance, and includes instruments known as the 
u megger ” testing set and the “ ducter ” potential ohmmeter. 

THE MEGGER TESTING SET. 

The megger testing set consists of a moving-coil ohmmeter com¬ 
bined in one case with a magneto generator, the latter being wound 
to give as high as 1,000 volts in some patterns. The idea is to pro¬ 
vide a portable apparatus which can be operated by an ordinary 
workman and which will give by direct indication in a few seconds 
the value of an unknown resistance. As the name indicates, the 
megger is especially adapted to measure high resistances, the upper 
reading of the scale corresponding to from 10 to 2,000 megohms in the 
stock patterns. A great advantage of instruments of this kind is 
that they determine insulation resistance with the working voltage 
applied to the object under test. 

The details of construction of the megger have been worked out 
very carefully, as may be realized from the fact that the whole instru¬ 
ment, including the ohmmeter, the high-voltage generator with its 
commutators and carbon brushes, and the gearing with its constant- 
speed clutch, is sealed at the factory and is sold under a five years’ 
guaranty. 

A special modification, the “ bridge megger,” has a master switch 
to enable it to operate either as an ordinary megger or in conjunction 
with an external resistance box as a Wheatstone bridge; in the latter 
case the moving-coil instrument is used as a. galvanometer. This 
allows of accurate measurements of resistances from 1 ohm to 10,000 
ohms; however, the possible limits of measurements are much greater. 

THE DUCTER TESTING SET. 

The Wheatstone-bridge method, even in the laboratory, fails to 
give accurate results for very low resistances. However, it is neces¬ 
sary that methods be provided for the measurement of such important 
low resistances as those of switch contacts, rail sections, test pieces 
of cast or drawn metals or alloys, fuses, circuit-breaker coils, etc. 
In the laboratonr this need is met by the use of the Kelvin double 
bridge and similar methods, and with care a very high accuracy can 
be obtained. For engineering and commercial work, however/high 
accuracy is wholly unnecessary, and the complications and refine¬ 
ments of the laboratory can not be practiced by the ordinary work¬ 
man. What is needed is a simple method which gives moderate 
accuracy (5 per cent is ample in many cases), combined with porta¬ 
bility, simplicity, and quickness of operation. To meet this need 
Evershed & Vignoles (Ltd.) have recently brought out the “ducter,” 
which is based on principles similar to those used in the megger. 

The ducter is a low-resistance ohmmeter having two moving coils 
rigidly attached to each other and moving in the field of a permanent 
magnet. An auxiliary two-volt storage cell passes a current through 
a suitable shunt within the instrument and through the unknown 




ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 29 

resistance. One of the moving coils is connected in series with a re¬ 
sistance coil, and this “ control circuit ” is connected across the shunt. 
Since connections to the moving system are made by very thin spirals 
of the smallest possible torsion, the controlling force is practical!}' 
proportional to the current flowing through the circuit whose resist¬ 
ance is to be measured. Potential terminals are placed on this cir¬ 
cuit at the points between which the resistance is to be measured, and 
these points connect by flexible conductors to the second moving coil. 
The deflecting force thus varies as the resistance of the circuit be¬ 
tween the potential points. By the use of 3 shunts and graded 
resistances in the control circuit the ductor is given 5- ranges. The 
first range is direct reading 0 to 500 microhms; one can read by 
estimation to the nearest microhm. The other 4 ranges are direct 
reading, except for the necessity of using the factors 10, 100, 1,000, 
or 10,000. The highest value measured with the ducter is thus 5 
ohms. Accessories are furnished with the ducter to enable the spe¬ 
cific resistance of samples to be measured without calculation. The 
ducter and the series of meggers have an enormous combined range, 
namely, from a full-scale reading corresponding to 0.0005 ohms to 
full-scale reading for 2,000,000,000 ohms. 

• THE DIONIC WATER TESTER. 

The “ dionic water tester’’ of Digbv & Biggs is virtually a megger 
used to determine the specific resistance of a sample of water. The 
water is contained in a glass U tube, in each side of which is immersed 
a platinum electrode whose area is sufficiently large to prevent ap¬ 
preciable error due to the formation of gas bubbles. A mean value 
of the polarization electromotive force is allowed for in the calibra¬ 
tion of the apparatus; since the dynamo voltage is 100, small varia¬ 
tions of the polarization electromotive force do not introduce appre¬ 
ciable error. The scale of the ohmmeter (which is built in with the 
generator) is graduated in conductivity units for w T hich at present no 
simple name exists; one such unit is the reciprocal of a megohm 
(which might be called a micromho 1 ) per centimeter cube. 

The conductivity of very pure water is exceedingly low; even 
small traces of impurity, however, will greatly increase the con- 
ductivit}'. A striking experiment witnessed by the writer will illus¬ 
trate this. From a beaker of very pure w r ater a sample was poured 
into the U tube; on turning the generator handle the needle of the 
ohmmeter showed that the conductivity was about 1.5 units. The 
thumb and forefinger were then rubbed together for a moment in the 
water remaining in the beaker. A sample of this water now showed 
by test a conductivity five times as great. 

The dionic tester thus enables the user to detect very small traces 
of impurity in water; in the case of dilute solutions of a known salt, 
the amount of salt present per unit of volume can be determined. 
The dionic tester is applicable to the measurement of the hardness of 
water, thus enabling rapid checks to be made of the operation of 
water-softening plants. It may be used for detecting leakage in sur¬ 
face condensers by periodically testing samples of water from the 

1 This word would perhaps be objectionable in practice on account of its similarity to 
“ microhm.” 




30 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

hot well; leaks may thus be discovered and repaired before they be¬ 
come serious. With the condenser in good order, boiler priming may 
be detected and measured. Other applications of the dionic tester are 
the detection of the pollution of streams and the checking of the 
operation of sewage-purification works. Many other applications 
will doubtless be found as the instrument becomes better known. 

FERRANTI (LTD.). 

BUILDINGS AND EQUIPMENT-EMPLOYEES. 

The electrical engineering works of Messrs. Ferranti (Ltd.) are 
located in Hollinwood, a suburb of Manchester. The present com¬ 
pany was incorporated in 1891, but Ferranti apparatus dates back 
much further, S. Z. de Ferranti being one of the pioneers in electrical 
development. 

The buildings are of brick and are lighted by windows and from 
the roof. The machine tools are arranged along the main walls, and 
are group-driven by 220-volt direct-current motors and line shafting. 
The firm buys electrical energy, in the form of 3-phase 6,000-volt 
current, from the local lighting company, and converts it to direct 
current for distribution about the works. 

About half the machines are English and half American. The 
latter are mainly automatic machines and small turret lathes, of both 
of which the company has a large number in use. The conditions 
under which the machines work are severe, in that they are run night 
and day. A number of heavy Cleveland automatics are working on 
mild-steel rods about 1 inch in diameter, and have been run night and 
day for the last three years. The American machine tools are well 
liked. 

The firm’s employees number about 1,700, of whom about 60 per 
cent are engaged in the manufacture of electric meters and instru¬ 
ments. Practically no female labor is employed, the reason assigned 
being that the neighboring textile mills employ all that is available, 
at wages greater than can be paid for electrical work. Boys wind 
coils, run turret lathes, and do assembling, testing, and adjusting. 
The working week consists of 52^ hours, the single-break system 
being used. Labor unions are recognized and union wages are paid. 
There has been practically an entire absence of strikes during* the 
last 10 years. 


DIRECT-CURRENT METER, MERCURY TYPE. 

The products of the company include transformers, switchboard 
and control apparatus, electric meters and instruments, and electric 
heating and cooking apparatus. By far the most important item is 
that of meters, of which the company is making about 10,000 per 
month, about half of this number being for direct current. 

The Ferranti direct-current meter, Hamilton patent, is of the mer¬ 
cury type. The company admits that good accuracy may be obtained 
from commutator meters when in good condition, but claims that 
this accuracy is soon lost in service on account of increase of brush 
friction and deterioration of brush contacts. They state that their 
20 years’ experience with mercury motor meters has enabled them to 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 31 

overcome the difficulties attending the use of mercury, and in proof 
of this they cite the fact that their meters have been adopted by all 
the large supply companies of England after severe and extended 
tests. Their mercury meter as made for service use is an ampere-hour 
meter, the dials being marked to read Board of Trade units (kilowatt 
hours) at a stated voltage. 

In this meter the copper disk is immersed in mercury in a chamber 
composed of nickel-plated brass top and bottom plates bolted together 
with a separating ring of fiber or hard rubber; the inner surfaces of 
the brass plates being further protected by press-pan sheet insulation. 
Into each brass plate are riveted two mild-steel pole pieces, to 
which strong permanent magnets are attached. The current enters 
the mercury by the contact at the right, flows radially across the 
disk between the right-hand pair of pole pieces, leaves the bath 
at the central contact, and flows through a compounding coil of a 
few turns wound on a mild-steel crossbar joining the two bottom pole 
pieces, which are of like polarity. The disk is caused to rotate by 
the interaction of the current flowing through it and the magnetic 
field between the right-hand pole pieces. Both pairs of pole pieces 
induce eddy currents in the disk, and furnish the necessary drag to 
make the speed of the meter proportional to the current. However, 
the variation of mercury friction is such that if the compounding 
coil were not used the meter would be slower the heavier the load. 
The current is passed through the compounding coil in such a direc¬ 
tion that, as the current increases, the right-hand (driving) field is 
strengthened and the left-hand weakened. This makes the driving 
force greater than it would otherwise be, but leaves the braking 
force for a given speed unchanged, since both fields contribute to 
this, and one is strengthened and the other weakened by practically 
the same amount. 

The copper disk is platinum plated and enameled to protect it from 
the mercury; the edge and center are left unplated, and are amal¬ 
gamated in order to make good contact with the mercurjL The 
mercury is purified very carefully, a detail which experience has 
shown to be quite necessary for good results. 

The spindle that carries the disk is of nonrusting alloy. The worm 
is milled in this spindle by a specially designed machine. A steel 
pivot is inserted at each end of the spindle, each pivot being carried 
in a replaceable sapphire jewel. The mechanical balance of the rotat¬ 
ing system is adjusted by three small nuts, and a weight carried by 
the spindle causes the whole system just to sink when the mercury 
is at the normal level. A sealing device, which contains no rubber 
or other perishable material, is used to prevent escape of mercury 
when the meter is to be carried about or shipped. 

The case is of cast iron enameled inside and out after a careful 
cleaning to avoid trouble due to iron particles or grit entering the 
working parts when in service. Substantial cast-iron cases are pre¬ 
ferred in England as a rule, and the head of the meter department 
of a large Italian company expressed his strong preference for such 
cases because of their ability to stand the rough handling of the class 
of labor used for carrying meters and placing them in position. The 
joint between cover and case is made with a gasket, and is said to be 
dust proof and water-tight. The carrying handle is useful for meters 
with cast-iron cases; it is a feature that has evidently been consid- 


32 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

ered unnecessary by American manufacturers. Above 50 amperes 
shunted meters are used. Special cases are used having a compart¬ 
ment at the back for the shunt, so that the whole is self-contained. 
The starting current of these meters is given by the maker as from 
0.03 ampere for a 1.5-ampere meter to 2 amperes for the 1,200-ampere 
meter. The drop at full load is about 80 millivolts. 

V 

CYCLOMETER DIALS. 

While some forms of cyclometer dials have been found to be open 
to serious objection, Messrs. Ferranti consider the type made by 
them fully as reliable as the clock dial. The early cyclometer dials 
were, as the name indicates, simply adaptations of the familiar 
bicycle cyclometer. They had the defect of putting a variable fric¬ 
tion load on the meter that became greater as more and more num¬ 
bers had to be moved; 
as the higher wheels 
were idle for long pe¬ 
riods, opportunity for 
corrosion and sticking 
was present. The fric¬ 
tion to be overcome in 
turning several num¬ 
bers at once is said to 
have been at times 
great enough to stop 
the meter. Such a dial 
mechanism is still used 
by some makers, but is 
especially objection¬ 
able in view of the re¬ 
duced current con¬ 
sumption of metal- 
filament as compared 
with carbon lamps. 

The firm states that 
the patent device used in its cyclometer dial avoids this difficulty. 
This device is shown in figure 1. A weight, partly counterbalanced, 
is carried on the spindle immediately over the number hole farthest 
to the right. This weight is slowly raised by the revolution of the 
spindle until it is just past its top position, when it falls suddenly, 
changing the figures definitely from one reading to another reading 
one unit higher. The weight is sufficient to change all the figures 
at once. 

To facilitate testing, a small circle and pointer are provided on 
the dial, each division being one-tenth of a unit shown by the lowest 
number wheel, and a similar dial, with white figures on a black 
ground, is arranged above the dial, each numbered division being 
one one-hundredth of a unit of the lowest number wheel, and being 
further subdivided into thousandths. 

While the writer agrees in general with the ideas which have gov¬ 
erned United States practice of late, namely, that meter dials should, 
for ordinary house sizes, read kilowatt hours on the lowest dial in¬ 
stead of tenths as in the past, and that dials should be kept free from 



Fig. 1.—Ferranti cyclometer dial. 






ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 33 

everything unnecessary that may distract the attention or cause error, 
he has always held that from the consumer’s point of view a meter 
test by disk revolutions alone is not complete, but needs to be supple¬ 
mented by a check of the gearing ratio between the spindle and the 
lowest dial. This usually requires removing the dial from the meter, 
which gives opportunity for accidents to worm wheel or meter spin¬ 
dle. It might be well for American makers to consider the desir¬ 
ability of providing a tenths or hundredths dial to be used for testing 
purposes. To make this dial inconspicuous, it could be carried above 
the regular dial front, as is done in the Ferranti meter. 

VARIOUS TYPES OF METERS. 

The three-wire direct-current meter consists of two regular two- 
wire meter mechanisms contained in a single case, each indicating on 
a separate dial. These are made in sizes up to 150 amperes. The 
battery meter is similar to the three-wire meter, but each element is 
provided with a pawl to prevent backward rotation. One element 
indicates the total charge given to the battery, the other the total 
discharge. 

The two-rate direct-current meter has the usual operating element, 
but with a double set of dials. An electromagnet is used to throw 
into gear the upper or the lower dial; this magnet is wound with fine 
wire and connected, with a suitable resistance, in a shunt circuit 
across the line. A time switch is used to close this circuit during the 
part of the 24 hours that the high rate is in effect. This time switch 
may be used to operate the magnets of a number of meters. The 
shunt circuit of each meter requires about IT milliamperes; this is 
flowing only during the time the high rate is in effect. 

Prepayment meters are made for direct and also for alternating 
current. The meter element is of the standard type and shows the 
total consumption on the usual cyclometer dial. The prepayment 
dial shows the total coins deposited up to 999, and the coins unused 
up to 12. The knife switch has a quick double break with an arcing 
distance of 1J inches. The customer in rotating the handle to intro¬ 
duce the first coin closes the switch and also raises a weight that is 
later released by the meter and opens the switch. The meter acts on 
the release action through a train of wheels geared down 55 to 1 to 
reduce the frictional load on the meter. These meters are made in 
3, 5, and 10 ampere ranges, the weight being 25 pounds. 

The traction meter is a modification of the regular direct-current 
type, the changes introduced being as follows: The bottom jewel is 
spring supported; an ordinary bearing is used at the upper end of the 
spindle in place of the usual jewel; the pivots are stronger, and the 
bottom one is rounded to a larger radius; the rotor is very light, and 
the meter is heavily shunted. It is said to be capable of standing 100 
per cent overload for 10 minutes, and is guaranteed accurate within 
2J per cent from 10 per cent to full load. 1 

1 The following note from Daily Consular and Tirade Reports of Oct. 24, 1910, refers 
to the saving which may be made by using meters on street railway cars : “ The British 
Tramways and Light Railways Association prints interesting information relating to 
the economy in current consumption in Continental towns as the result of the adoption 
of car meters, the highest saving recorded being over $100,000 a year by the Berlin com¬ 
pany which has 1,500 cars. There is still on the Continent some preference for the time 
meter which simply shows how long current has been in use. In England the ampere- 
hour meter looks more likely to retain general favor. Berlin, Amsterdam, Cologne, and 
other cities claim that the hour meter is simpler, cheaper in first cost and maintenance, 
and better understood by the drivers. 


65509°—13-3 




34 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

INDUCTION METERS. 

Before describing the modern induction meter, the manufacture of 
which has recently been taken up by the company, it will be of inter¬ 
est to describe the older form, which is still manufactured and of 
which many thousands are in service. 

The series winding is wound in four coils on a cast-iron stator; 
below this are the mild-steel shunt core with two cast-iron polar 
projections, the shunt coil, and a cast-iron tube with screw for hold¬ 
ing the shunt core in place. The use of cast iron and solid steel for 
these portions of an alternating-current meter is rather startling to 
one who is accustomed to the more common practice of using lami¬ 
nated magnetic circuits; in spite of this, the performance, as given by 
the maker’s curves, is a good one. The torque is given as 20 milli¬ 
meter grams, and the weight of moving element 23 grams. The full- 
load speed (for all capacities) is 40 revolutions per minute. The case 
is of cast iron, as in the direct-current meter. The same type is also 
made as a three-wire meter, the current winding having two strands. 
The shunt loss of the preceding meters is given as 2 watts for volt¬ 
ages up to 250 and 4 watts above this to 500 volts, both at 50 cycles. 
The drop in series coil of the 10-ampere single-phase meter is given 
as 0.15 volt, and inversely proportional to the current for other sizes 
between 3 amperes and 25 amperes; above 25 amperes the drop is 
somewhat greater than this formula would give. The starting cur¬ 
rent is given as about 1 per cent for 3 and 5 ampere sizes, 0.5 per cent 
for 10 to 25 ampere, inclusive, and 0.25 per cent for 50 to 100 ampere 
meters, inclusive. 

The polyphase meter has two driving elements, as just described, 
working at diametrically opposite positions on a larger aluminum 
disk. The moving system weighs 45 grams, and the torque is given 
as TO millimeter-grams. The speed with both elements at full load is 
40 revolutions per minute. The figures given for shunt loss and series 
coil drop of single-phase meters apply, with the proper modifications, 
to polyphase meters. 

The Ferranti “Type C” induction watt-hour meters embody the 
features of construction and operation that characterize modern 
induction meters. The disk is of aluminum, and the full-load speed 
is 40 revolutions per minute. The full-load torque is given as 50 
millimeter-grams, and the weight of the moving element is 27 grams. 
The shunt loss is given at 1.5 watts; series loss up to 25 amperes 
capacity, 1 watt; the starting current of the 5-ampere size, 0.03 
ampere. The weight up to 25 amperes capacity is 10.5 pounds with 
sheet-steel cover, or 11 pounds with glass covers. 

The company obtains its supplies and materials from England, 
France, and Germany and markets its products all over the world, 
with the exception of the United States, where the high tariff makes 
competition with American products impossible. 

NALDER BROS. & THOMPSON (LTD.). 

ORGANIZATION, BUILDINGS, AND EQUIPMENT. 

The firm of Nalder Bros. & Thompson (Ltd.) was established by 
F. H. Nalder and H. Nalder in 1884 as Nalder Bros. C. W. S. Craw¬ 
ley joined them in 1886, the name of the firm being changed to Nalder 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 35 

Bros. & Co. Alfred Soames also joined the firm a little later. In 
1896, the business having increased greatly, it was divided; the 
ammeter, voltmeter, and switchboard business was taken over by 
F. H. Nalder and E. Thompson under the name of Nalder Bros. & 
Thompson. In 1899 the business was converted into a limited 
liability company, and an additional factory building was secured at 
Dalston, in the northern part of London. 

The principal office is located at 34 Queen Street, in the east-central 
district of London. Here also the work of coil winding, assembly, 
and testing of instruments is carried on, the work occupying several 
floors of the building. The factory at Dalston produces parts for 
stock, which are assembled at the Queen Street works. The Dalston 
factory is a three-story brick building, and is well equipped with 
machine tools, including full-automatic screw machines, ordinary 
turret lathes, engine lathes, milling machines, tapping machines, 
grinders, and drills. Included in the above are machines by Brown & 
Sharpe; Pratt & Whitney; Cincinnati Milling Machine Co.; Brainard 
Milling Machine Co.; Dwight Slate Machine Co.; Washburn Shops 
of the Worcester Polytechnic Institute; Hendey Machine Go.; and 
other American firms. The machines are driven by a gas engine 
through the usual line and counter shafting. The exhaust from this 
engine is carried up to the top floor and used to heat the plating 
baths before it escapes into the atmosphere. Gas furnaces are used 
for hardening, tempering, melting solder, etc. The temperatures for 
hardening and tempering magnets are determined by thermocouple 
and millivoltmeter. After being magnetized, the magnets are arti¬ 
ficially aged and also numbered, tested, and marked with the strength, 
in arbitrary shop units. They are then stored for a period of time 
and again tested before assembly. 

An interesting method of speed variation is used in the coil-winding 
machines at the Queen Street works. The spindle carrying the coil 
to be wound is driven by a small pulley, which is in contact with a 
special friction disk mounted on the shaft of an ordinary fan motor 
from which the blades have been removed. The friction disk has a 
spherical surface, whose center is in a vertical line through the center 
of the base of the motor; the motor is arranged to swivel about this 
vertical axis by pressure on a treadle. The arrangement is similar to 
that used in friction disk drills; it gives quick control of the speed 
of winding over the whole range from zero to maximum. 

All instrument coils are dried in a vacuum* using an incandescent 
lamp as a heating element in the vacuum chamber. This practice 
has been followed by the firm since about 1888. 

METHODS OF TESTING. 

For alternating-current testing two alternators are driven by a 
direct-current motor. By varying the size of the driven pulley, 
frequencies from 25 to 100 can be obtained. Kelvin balances and 
Siemens electrodynamometers are used as standards for alternating- 
current testing. For the measurement of high voltages an arrange¬ 
ment due to Ayrton and Mather is used, consisting of a large number 
of coils in series, forming a high-resistance “ volt box.” Around a 
portion of this resistance is connected an electrostatic voltmeter 
reading up to 2,000 volts. The coils composing the high resistance 


36 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

are mounted in a frame in such a way as to give high insulation and 
dielectric strength; taps are brought out at- intervals, so that for 
various values of voltage applied to the total resistance, approxi¬ 
mately full-scale deflection of the electrostatic voltmeter will be 
produced. The maximum current in the resistance coils is about 
0.01 ampere. The maximum voltage measurable with this appa¬ 
ratus is 40,000; it is used for testing potential transformers and 
high-range electrostatic voltmeters. 

For direct-current testing the potentiometer is used as ultimate 
standard, and portable instruments compared at intervals with the 
potentiometer are used as working standards. 

CONDITIONS OF LABOR-PRODUCTS OF THE FIRM. 

The number of employees is about 180; of these, about 15 to 20 
per cent are girls. The hours of work are from 8 a. m. to 6.30 p. m. 
(with an hour for lunch at noon), except Saturday, when the works 
close at 1 o’clock. 

The products of the firm include circuit breakers, switchboard and 
portable instruments, and instrument transformers. 

Permanent-magnet moving-coil instruments for switchboard use 
are made in four sizes of round pattern, with dials from 5 to 11 inches 
in diameter, bases 6 to 12 inches in diameter. They are also made in 
four sizes of sector pattern, with scales 5 to 12 inches long, in addi¬ 
tion to two older patterns still called for. The largest sector instru¬ 
ment has two movements astatically arranged; this construction 
reduces error due to stray magnetic fields and would seem to be very 
suitable for voltmeters. A number of forms of edgewise instruments 
are also supplied. Ammeter shunt leads are provided at the shunt 
ends with strips of alloy several inches in length of the same mate¬ 
rial as is used for the shunts. The purpose of these strips is indi¬ 
cated by the name applied to them, “ counterthermal electromotive 
force ends.” Two types of portable moving-coil instruments are 
made; a “ portable standard,” with enameled metal cases of the sector 
form, and a “ portable ” at a lower price, in wooden case. Testing 
sets are also made, one form having a multi-range voltmeter and a 
millivoltmeter, the two movements being mounted in one case, and 
shunts being provided to give three or four ranges; the other form 
consists of a single moving-coil instrument provided with a change¬ 
over switch to enable it to serve either as a voltmeter or as a milli¬ 
voltmeter, with shunts. 

Soft-iron instruments are made on the repulsion principle, the iron 
used being specially treated to reduce hysteresis errors. This line 
includes two sizes of round pattern in iron cases, a smaller “ gauge 
type ” round pattern for use with motors, and a round-pattern instru¬ 
ment with a 3-inch dial. All the preceding are air-damped and are 
listed with gravity control, though spring control is supplied at an 
extra cost. Several sizes of round-pattern instruments in brass cases 
are still made to meet a demand for this form; these have gravity 
control and are undamped unless otherwise ordered. In addition, 
soft-iron instruments are made in several sizes of sector and of edge¬ 
wise pattern, and also in .the horizontal edgewise pattern familiar in 
the United States. 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 37 
SWITCHBOARD WATTMETERS-ELECTROSTATIC VOLTMETERS. 

A switchboard wattmeter (round pattern, 8-inch dial, 9.5-inch 
base) is made by the firm after designs by Dr. C. V. Drysdale. It 
differs from the usual forms in having a laminated iron magnetic 
circuit, around which is wound the series coil; the potential coil 
swings in a gap in the magnetic circuit. The use of iron greatly 
increases the torque, and thus makes possible the use of stronger 
control springs. It is stated that the instruments are accurate on 
low power factors and are free from error due to variation in fre¬ 
quency and wave form; also, that they are suitable for use with 
direct current, the hysteresis error being said to be practically neg¬ 
ligible. These wattmeters have magnetic damping. 

Electrostatic voltmeters for switchboard use are made with piv¬ 
oted moving element, in round-pattern brass cases, with upper 
limits of 1,200 to 6,500 volts. A modified form of somewhat lower 
cost is made in practically the same ranges, in an iron case. In the 
brass-case form a neat device is used to make it safe to replace the 
self-contained fuses without disconnecting the line wires from the 
terminals. A hard-rubber block is attached to one end of a brass arm, 
the other end of the arm being hinged to the case. The hard- 
rubber block carries the terminals to which the line wires are at¬ 
tached; metallic extensions of these terminals enter insulated open¬ 
ings in the case, near the base, when the hinged arm is pushed down, 
and make contact with the ends of the removable fuses. By raising 
the arm the terminals are swung away from the case, and the fuses 
may be readily replaced. 

RECORDING INSTRUMENTS-CURRENT TRANSFORMERS. 

Recording instruments are made in the permanent-magnet moving- 
coil type, and also in the moving-iron type; both types are supplied in 
switchboard and in portable forms. The soft-iron type for switch¬ 
board use must be adjusted for a particular frequency, unless a special 
compensation for frequency, at extra cost, is ordered; it is stated 
that this compensation makes the instrument read correctly on any 
frequency, and also on direct current. All recorders are oil-damped, 
except portable recording voltmeters. Two forms of chart are used. 
The single-revolution chart is wound around a cylindrical drum, and 
must be replaced after one revolution of the latter, which is made 
in 6, 12, or 24 hours. The continuous-record chart consists of a roll 
of paper 63 feet long. The drum for the latter has a set of needle 
points on one side, which drive the paper forward; it is thus unnec¬ 
essary to perforate one edge of the chart. 

Current transformers are made in open type for use on circuits up 
to 2,500 volts and in inclosed (oil-immersed) type up to 12,000 volts. 
The open type has a wound primary coil up to 250 amperes; the bar 
type is supplied for 300 to 5,000 amperes. The standard secondary 
full-load current is 5 amperes. Potential transformers of the stand¬ 
ard type are rated at 50 watts, 40 cycles, and give 110 volts on the 
secondary with rated primary voltage. Up to 2,500 volts the open 
type is supplied; above that, up to 12,000 volts, the oil-immersed 
type. 


38 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

Other switchboard instruments made by the firm include ground 
detectors, moving-coil type, for mine use; round-pattern frequency 
meters, vibrating-reed type; round-pattern power-factor meters and 
synchronizers. 

THE OHMER-MARKETS. 

The ohmer (Cox’s patent) is of interest on account of the prin¬ 
ciple involved. It consists of a pivoted electrostatic instrument 
whose operating parts consist of four sets of fixed quadrants, each 
set having 13 vanes, the space between adjacent vanes being about 
0.2 inch, and a moving element consisting of 12 fishtail-shaped vanes 
of mica covered with aluminum. This construction is said to be 
much better than the one using solid aluminum vanes, the mica 
being much more elastic and not so readily deformed. A hand mag¬ 
neto generator wound for 500 or 1,000 volts is connected through a 
high resistance to the terminals to which unknown resistances are 
to be connected, and two sets of fixed quadrants are joined to each end 
of the high resistance. The moving vane is connected to the com¬ 
mutator brush which goes directly to one of the “ unknown ” termi¬ 
nals. When the resistance between these terminals is infinite there 
is no fall of potential along the resistance coil to whose ends the two 
groups of fixed quadrants are joined, so that these groups are at the 
same potential; the moving element will take up a position such that 
symmetrical portions of it are inclosed by the two groups of fixed quad¬ 
rants. If the “ unknown ” terminals are joined by a wire of negligible 
resistance, the moving element will have the same potential as one 
of the fixed elements, and will turn until it is symmetrically inclosed 
by the other fixed element. For values of resistance across the 
unknown terminals intermediate between zero and infinity, the mov¬ 
ing element will take up intermediate positions, and the scale may 
be graduated by trial. The upper limits for which the instrument is 
made are 20, 50, and 100 megohms; each instrument has a switch 
for shunting the internal resistance down to one-tenth of its value, 
so as to reduce the range in the same proportion. The 1,000-volt 
ohmer may be fitted with two vibrating reeds under the window 
opening of the instrument. One of these reeds will be set in vibra¬ 
tion when the speed is that which generates an electromotive force 
of 500 volts; the other reed responds when the electromotive force 
is 1,000 volts. 

The ohmer is independent of voltage, in principle; in practice this 
depends upon the ratio of the actuating torque, for a given displace¬ 
ment of the moving element from its true position, to the torque of 
the flexible conductor used to make connection with the moving 
element, and also to the frictional torque. The latter is a difficulty in 
the way of making satisfactory pivoted electrostatic instruments; 
in the present instrument the ohmmeter and the generator are mounted 
on the same base, and the vibration transmitted from the generator 
tends to prevent frictional errors. The prominent advantages of the 
instrument are the lightness of the electrostatic ohmmeter as compared 
with permanent-magnet moving-coil ohmmeters, and its independence 
of stray magnetic fields. 

The firm uses British materials almost exclusively. Its product 
is marketed in Great Britain, Canada, English colonies, and abroad 
generally, but very little is sold in the United States on account of 
the high duty. 



ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


39 


ROBERT W. PAUL. 

BUILDINGS AND EQUIPMENT. 

The Newton Avenue works of Robert W. Paul are located at New 
Southgate, one of the northern suburbs of London. The business was 
established in the city of London by Mr. Paul in 1891, and the present 
works were erected in 1902-3. 

There are four buildings in all, with a total floor space of about 
20,000 square feet. All are of brick, and were planned especially for 
instrument manufacture. One two-story portion of the main build¬ 
ing contains, on the ground floor, the drawing and other offices, store¬ 
rooms for materials and finished apparatus, and the room where 
apparatus is inspected before shipment. The floor above is divided 
into five rooms, which are equipped for the winding of galvanometer 
coils and of resistance coils, and for the testing and adjustment of re¬ 
sistance apparatus, galvanometers, millivolt meters, inductance appa¬ 
ratus, etc. The other two-story portion of the main building contains 
the power plant and storage batteries. The prime mover is a gas 
engine operated on producer gas; it drives the machine shop by means 
of a line shaft, and also two direct-current dynamos used for battery 
charging. In addition to a battery giving a usual lighting voltage, 
several large cells are provided for heavy currents at low voltages, a 
special low-voltage generator being provided for charging them. 
A motor-generator set is provided for supplying alternating currents, 
and may be operated from the engine-driven generator, or, when 
steadiness is essential, from the storage battery. 

The one-story portion of the main building is the main workshop; 
it has a saw-toothed roof. The equipment includes, in addition to 
the usual bench and engine lathes, turret lathes, milling machines, 
drills, sheet-metal working tools, and machines for grinding, gear cut¬ 
ting, engraving, etc. Included in the above are several machines of 
American make. 

An interesting feature of the assembly benches in the main work¬ 
shop is the provision for securing increased bench room at times by 
swinging unused bench lathes back against the wall. The counter¬ 
shaft for each lathe is on the top of the bench close to the wall; it has 
a cast-iron arm that swings in a vertical plane perpendicular to the 
wall, about the axis of rotation of the shaft, and carries the lathe at 
its outer end. Thus the lathe may be swung back at any time with¬ 
out removing the belt or changing its tension. Opposite the assembly 
benches are the lighter engine lathes, small drills, milling machines, 
and shapers. 

A complete duplicate set of standard parts is kept on racks in 
the drawing office, where they are often referred to in designing 
new apparatus. One sample of each pair has a red tag attached. 
This sample is available for mailing to makers of standard parts, for 
quotation, or for supply. The other sample bears a green tag and is 
not allowed to leave the works. 

TESTING MICROAMMETERS. 

A labor-saving device is used for calibrating microammeters, 
which are an important product of these works. A special dial rheo¬ 
stat has its resistance so adjusted that when a certain standard 


40 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


amount of additional resistance is in series with it, and an electro¬ 
motive force of 0.1 volt is applied to the resulting circuit, currents 
of five, ten, fifteen, etc., hundred-thousandths of an ampere will flow 
for the successive positions of the dial. The current is supplied by a 
small storage cell, the dial rheostat and external resistance being 
tapped off from about one-twentieth of a resistance connected across 
the cell. A simple one-point potentiometer arrangement enables the 
standard drop of 0.1 volt to be maintained by the occasional adjust¬ 
ment of a slide rheostat. The value of the external resistance used 
in series with the dial rheostat is greater than the resistance of any 
microammeter to be tested, and hence the external resistance may be 
reduced by an amount equal to the resistance of the particular mi¬ 
croammeter under test. Therefore no error is caused by the resist¬ 
ance of the microammeter. This arrangement may be extended, 
when the nature of the product demands it, by having other points 
on the potentiometer arrangement, so that standard potential drops 
of higher or lower values may be had and checked against the 
standard cell. 


MAGNETIC PURITY OF MATERIALS. 

For testing the magnetic purity of samples of insulated wire, coil 
frames, and fittings, as used in the construction of galvanometers, an 
apparatus is used based on a similar apparatus described by Madame 
Curie. This apparatus contains a long phosphor-bronze suspension 
strip, as used in moving-coil galvanometers. The lower end of the 
strip carries a horizontal “ boom,” consisting of a brass wire about 8 
inches long. One end of the boom carries a sector-shaped sheet of 
copper, which moves in the jaws of a strong damping magnet; the 
sample of material to be tested is hung from the other end of the 
boom, being slid along to such a position as will make it balance the 
weight of the damping disk and bring the boom to the horizontal 
position. A second damping magnet, with vertical air gap, is 
brought into position so that the sample under test hangs freely in 
its gap. This second magnet is carried on a support that is pivoted 
at a point below the suspension and in line with the latter; the sup¬ 
port may be slowly rotated from without when the glass sides of the 
case are in place to screen the system from air currents. If there are 
magnetic impurities in the sample, it will be dragged along by the 
magnetic field until the torque of the twisted suspension is greater 
than that due to the magnetic attraction, when the coil will swing 
free from the magnetic field. A galvanometer mirror is carried on 
the suspension; by means of a lamp and scale, the magnitude of the 
deflection from the initial position may be read. It is not necessary 
to reduce the result to absolute units of any sort, as the relative be¬ 
havior of various lots of materials and the permissible limit of mag¬ 
netic impurity may be determined by experience. 

SPECIAL APPARATUS FOR MAKING INSTRUMENT SCALES. 

All instrument scales are especially made to suit the individual 
instruments. To do this work accurately and quickly, Mr. Paul 
devised and built special apparatus. This consists of two principal 
mechanisms. The instrument to be “ scaled ” is placed in the first 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


41 


one, and as the successive values of current are passed through it a 
radial arm (pivoted to rotate about a vertical line passing through 
the axis of rotation of the coil) is swung around so that the image of 
the instrument pointer is brought under the cross wire of a reading 
microscope carried on the radial arm. A stylus carried at the end of 
the radial arm is then depressed, making a pinhole in a paper chart; 
these pinholes are on an arc of a circle several times as large as the 
arc described by the end of the instrument poipter. By repeating 
this operation a chart is obtained which is really a scale to fit the 
law of the instrument, but magnified several times. This chart is 
marked with the serial number of the instrument and the range and 
figuring desired and sent to the scale-making room. Here it is put 
in the proper position in the second apparatus, which has a pointer 
carried at the end of a radial arm swinging about a pivot. A blank 
scale cemented to its supporting plate is then put under the radial 
arm, guide pins bringing it into the correct position. The radial arm 
carries a printing attachment, which may be provided with type for 
printing lines of various weights. The printing attachment is self- 
inking and automatically makes the changes in length of the fifth 
and tenth division lines. It is also possible to print either horizontal 
or vertical scales. 

LABOR CONDITIONS. 

The number of employees is about 85, of whom about 10 per cent 
are girls. These latter do the coil winding, scale making, and similar 
light work. The number of hours per week is 50 for the workshop, 
44 to 48 for the testing department, and 48 for apprentices, who are 
allowed time off to attend evening classes. The average rate of pay 
for daywork is, for journeyman instrument makers, 18 to 20 cents 
per hour; for piecework, 24 to 28 cents per hour. No trouble from 
strikes has been experienced. 

TYPES OF RESISTANCE APPARATUS MANUFACTURED. 

The types of resistance apparatus made by Mr. Paul include single¬ 
value standards, dial and plug boxes, Wheatstone and slide-wire 
bridges. Single standards of Reichsanstalt type are wound with 
manganin wire. The Drysdale compensated resistance standard is 
made with the object of securing great permanency combined with 
small temperature coefficient. With the first-named requirement in 
mind, all perishable organic substances (silk and varnish) commonly 
used in such standards have been avoided by the use of bare wire 
wound on porcelain supports. (A similar construction was proposed 
by Prof. F. W. Burst all and is described in the Proceedings of the 
Physical Society of London, vol. 14, p. 286.) To secure the smallest 
possible temperature coefficient, a constantan wire, whose resistance 
decreases slightly with increasing temperature, is plated with such a 
coating of nickel (whose resistance increases with increasing tem¬ 
perature) as will most nearly compensate the two opposing effects. 
If both metals had a linear variation of resistance with temperature 
it would be theoretically possible to secure perfect compensation. 
As both constantan and nickel depart somewhat from a linear varia¬ 
tion (in opposite directions), this is not possible. 


42 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

These coils are listed by Mr. Paul in three denominations, namely, 
1, 10, and 100 ohms. A question that will naturally arise is, Will not 
such coils be more troublesome to work with than manganin coils, on 
account of the large thermal electromotive force of constantan in con¬ 
tact with copper? For the 10 and 100 ohm coils this would probably 
not be of consequence; for 1-ohm coils and lower values it would 
seem possible to apply the same principle by nickel plating manganin 
which has been selected for negative temperature coefficient. This 
would avoid the thermoelectric difficulty. The temperature coefficient 
of magnanin is commonly given as positive, but varies considerably 
in different samples, and is sometimes negative. The temperature 
coefficient of a sample of manganin may be appreciably changed by 
annealing it. 

For resistance substandards of 0.1 per cent accuracy, and for 
standard types of plug and dial decade resistance boxes and bridges, 
Mr. Paul uses eureka alloy, though manganin is supplied if required, 
at an extra cost. 

The “ precision decade resistance,” made according to designs of 
A. C. Jolley, is an arrangement of manganin coils in a metal case for 
oil immersion, with some novel features of construction. The coils 
are wound on large brass tubes slit lengthwise to insure a certain 
amount of yielding, and covered with thin micanite tubes in place of 
the usual silk. Each decade of coils is mounted in a metal frame¬ 
work, with mica-insulated segments on the upper surface. This dial 
has the coils soldered to the segments and may be lifted out, since no 
connecting wires are used between the dials. Instead, a laminated 
copper brush is pivoted to make yielding contact, one end with the 
central ring of one decade, the other end with the segments of the 
next decade. Each dial is rotated by a crank, the set of coils revolv¬ 
ing under the fixed brush. Because of the large size of the coils, and 
the oil cooling, these coils will carry considerably greater currents 
than the usual small air-cooled coils. A click device is used to indi¬ 
cate to the sense of touch when the dial is central in each contact 
position. 

Another line of decade boxes and bridges has stationary coils of 
eureka wire wound on porcelain spools, the coils being proportioned 
to give low capacity and inductance. The 10-ohm coil of this type 
is stated to have a resultant inductance of 3X10 -7 henry. There are 
no live metal parts on the rubber top except the binding posts; the 
brushes and contacts are thus protected from dirt, and leakage is 
avoided. 

In another line of resistance boxes, plug contacts are used, the 
blocks being molded in the hard-rubber top, so that the surfaces of 
blocks and top practically coincide. This construction is used to 
prevent shifting of the blocks, which sometimes occurs where the 
blocks are screwed and pinned on the top. The insulation resistance 
between adjacent blocks is stated to be 10,000 megohms. 

Carbonized-cloth regulating rheostats, carbon-plate rheostats, rheo¬ 
stats for arc lamps, and other types are made for currents ranging 
from 1 to 500 amperes. 


UNIPIVOT INSTRUMENTS. 

The best-known instrument of Mr. Paul’s manufacture is probably 
the “ unipivot,” made in both moving-coil (permanent-magnet) type 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 43 

and electrodynamometer type. The distinguishing feature of these 
instruments is the use of a circular coil supported on a single pivot, 
the point of which is at the geometric center of the coil, and also at 
the center of gravity of the moving system. This construction allows 
the coil to swing freely without touching the core or pole pieces, and 
is said to give much less friction than the usual two-pivot construc¬ 
tion ; it also permits the raising of the pivot from the jewel for trans¬ 
portation. By using relatively light springs, the current sensitive¬ 
ness of the unipivot instruments is made quite large; for example, a 
350-ohm instrument with 150-division scale about 7 inches in length 
gives five divisions deflection per microampere; the time required for 
the index to come to rest, after closing the circuit, being about five 
seconds. If reduced sensitiveness is permissible, with a given coil 
resistance, the time can be reduced by using a stronger spring. The 
10-ohm galvanometer of the same pattern as the preceding gives one 
division for 2 microamperes, or 20 microvolts on the coil. Unipivot 
galvanometers have printed scales, and are not adjusted to any exact 
value of current (or voltage) per division. Similar instruments are 
made w T ith calibrated scales, as millivoltmeters, milliammeters, insula¬ 
tion meters, “ universal sets ” for measuring practically all direct- 
current quantities, and pyrometer indicators; the last are also made in 
horizontal edgewise pattern for mounting on walls. The “Ampall ” 
is a portable unipivot moving-coil instrument giving full-scale deflec¬ 
tion for 2 millivolts; a contact block is provided which has two 
potential points spaced at such a distance as will give a drop of 2 
millivolts on a copper conductor 1 square inch in cross section carry¬ 
ing 1,000 amperes; the scale is figured from 0 to 1,000, and is thus 
direct reading for such a conductor. With smaller or larger con¬ 
ductors, the reading multiplied by the cross section of the conductor 
gives the current; this calculation may be quickly made by a circular 
slide rule supplied with the instrument. The same instrument may 
be used for conductivity tests, using a 20-microhm copper resistance 
forming part of the outfit. 

Unipivot dynamometer instruments have the moving coil and 
pivot construction as in the permanent-magnet type. The moving 
coil is inclosed by the fixed coils. These instruments are made as 
milliammeters, giving full scale deflection for 20, 50, 100, or 1,000 
milliamperes. With the addition of series resistance (free from 
inductance and capacity) these dynamometers are made as volt¬ 
meters, with resistance of 50 ohms per volt. Wattmeters are made 
on the same principle, the special feature being the low ranges pos¬ 
sible. 

HIGH-FREQUENCY AMMETER AND GALVANOMETER. 

The Fleming high-frequency ammeter, as made by Mr. Paul, con¬ 
sists of a permanent-magnet unipivot instrument connected by 
flexible leads to a fine iron-eureka thermocouple which is located at 
the center of a copper wire carrying the current to be measured, 
or, if the latter exceeds 2.5 amperes, a portion of the current. The 
high-frequency galvanometer and the thermomilliammeter operate 
on the same principle; in the former, two wires (one iron, one eureka) 
are looped together at their centers, and held in X-form by springs; 
the high-frequency current to be measured enters on an iron terminal 
and leaves from a eureka terminal. The heating of the junction sets 


44 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

up an electromotive force in the remaining thermo junction, across 
which the galvanometer is connected. A current of 1 ampere gives 
full scale deflection. The thermomilliammeter operates in a similar 
manner, but the thermo junction is in a vacuum; the ranges made are 
0 to 10 and 0 to 20 milliamperes. These thermal instruments may 
be calibrated on direct current, since the wires carrying the current 
to be measured are small enough to keep the error from “ skin effect ” 
down to an amount negligible in practical work. 

POTENTIOMETERS, REFLECTING GALVANOMETERS, AND WATTMETERS.. 

The slide potentiometer made by Mr. Paul is electrically one dial 
plus a slide wire. The coils forming the dial are mechanically ar¬ 
ranged as two dials, one reading from zero up to about half the 
range, the other covering the remainder. The cadmium cell is pro¬ 
vided for, and the working current may be checked by throwing 
over a double-pole switch, regardless of the dial and slide-wire posi¬ 
tions. The long-range potentiometer, designed by Mr. S. W. Mel- 
som,' is electrically equivalent to one dial of 150 1-ohm coils plus a 
slide wire, but the 150 coils are mechanically distributed over a num¬ 
ber of dials. The thermoelectric potentiometer (Carpenter-Stans- 
field) has two dials, the remaining figures of the result being read 
on the galvanometer scale. 

Paul reflecting galvanometers are of the Avrton-Mather type, and 
have a closed auxiliary damping winding in addition to the main 
coil. By opening the damping circuit the galvanometer may be made 
ready for ballistic work. The Campbell “standard galvanometer” 
is a moving-coil instrument for use as a precision ammeter or volt¬ 
meter in connection with suitable shunts and series resistances. To 
avoid spring fatigue, a wide bifilar suspension is used. The deflec¬ 
tions are read by lamp or telescope and scale. 

The Duddell-Mather standard wattmeter is a torsion-head instru¬ 
ment designed to avoid sources of error as far as possible. It is an 
astatic instrument, with stranded fixed coils that may be connected 
in various groupings to secure a wide total range. Metal parts are 
avoided to prevent eddy current errors; air damping is used. The 
design is such that full scale deflection can be obtained, without 
overloading the coils, at power factor 0.1. For use in the potential 
circuit of this wattmeter, an oil-immersed series resistance of the 
Duddell-Mather “gauze” type is used. This “gauze” is a fabric 7.5 
inches wide, made of silk-covered eureka wire woven with silk 
threads. The construction gives low capacity and inductance, high 
insulation, and large cooling surface. A suitable length of the gauze 
is supported on porcelain insulators. 

INDUCTANCE APPARATUS-THERMOCOUPLES. 

Inductance apparatus made by Mr. Paul includes the Campbell 
variable mutual inductance; fixed self and mutual inductance stand¬ 
ards; the Campbell “microphone hummer” for supplying small 
currents at 800, 1,000, 2,000, or 8,000 cycles; and the Campbell vibra¬ 
tion galvanometer. 

In addition to the pivoted and sector patterns of the Ayrton- 
Mather electrostatic voltmeters, Mr. Paul makes Avrton-Mather 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 45 

reflecting electrostatic voltmeters, with range of 1 to 9 or 4 to 30 volts; 
also a torsion-head pattern with range up to 60 volts. 

Paul thermocouples are made with a rod of eureka alloy inclosed 
in an iron tube and insulated from the tube by steatite and magnesia, 
except at the end, where the iron and eureka are welded together to 
form the thermo junction. These are for use up to 900° C.; above 
this temperature, up to 1,600° C., a couple is used that consists of two 
wires of platinum-rhodium alloys of different percentages. These 
couples are said to be more durable and less liable to contamination 
than platinum-iridium couples. Unipivot indicators are used; for 
comparatively low ranges the indicator is fitted with the Darling 
compensator. This consists of a bar formed of two dissimilar metals, 
as used in thermostats and metallic thermometers, which is arranged 
to shift the zero reading of the indicator with changing room tem¬ 
perature by an amount such as will correct for the varying tempera¬ 
ture of the “cold junction.” Apparatus is also made for tempera¬ 
ture measurement by the electrical resistance method, using the Harris 
direct-reading indicator. The latter is a permanent-magnet moving- 
coil ohmmeter, whose construction is such that moderate variations 
in the working current produce no perceptible effect on the readings; 
it may be operated by a 4-volt storage battery or from a direct-cur¬ 
rent lighting circuit. It is electrically equivalent to a differential 
galvanometer with a third winding at right angles to the other two, 
the third winding providing the controlling force. 

HOT-WIRE OSCILLOGRAPH. 

The Irwin hot-wire oscillograph is about the last application that 
one would expect to make of the hot-wire principle, as hot-wire 
instruments are notably sluggish in coming up to final reading for a 
given current. The results obtained are remarkable. (Journal of 
the Institution of Electrical Engineers (London), vol. 39, p. 617; 
1907.) The principle of the instrument consists in using two fine 
wires under tension, carrying a light mirror; the wires are polarized 
by passing a direct current through them. The alternating current 
is then superposed on the direct, so that at any moment the direct 
current in one wire is increased and that in the other decreased. The 
mirror will thus be deflected to one side, the deflection being practi¬ 
cally proportional to the instantaneous value of the current, neglect¬ 
ing "thermal lag. The natural sluggishness of the hot wire, due to 
heat capacity, is overcome by modifying the current wave. For ex¬ 
ample, in using the hot-wire element in series with a high resistance 
to get the form of a voltage wave, a condenser is shunted around a 
part of the resistance. In order that the oscillograph shall give the 
true form of the voltage wave, the product of the capacity of the con¬ 
denser and the resistance around which it is shunted must equal a 
constant which depends on the heat capacity of the wires and their 
rate of losing heat. 

Mr. Paul secures his materials almost entirely from English 
sources; he stated that American dealers have not offered to supply 
him. His products are marketed throughout the world. While the 
high tariff tends to limit sales in the United States, he confidently 
expects to increase his sales there. 


46 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

H. TINSLEY & CO. 

The works of H. Tinsley & Co. are located at South Norwood, Lon¬ 
don, S. E. In addition to apparatus for submarine and wireless tele¬ 
graph work, such as siphon recorders, paper condensers, and arti¬ 
ficial line boxes, some electrical instruments of special types are made. 
It is of interest to note that telegraph condensers and artificial line 
boxes are adjusted in terms of the British Association microfarad, 
while for all other purposes the international microfarad is the unit 
employed. 

UNIVERSAL POTENTIOMETER-STANDARD CELLS. 

Tinsley’s “ universal potentiometer ” for direct currents has for the 
highest dial 19 10-ohm coils in series. A double contact lever runs 
over the studs of this dial, the 2 contacts inclosing 2 coils of the dial 
and being joined to the ends of a series of 10 2-ohm coils, which con¬ 
stitute an electrical vernier to the first dial. One moving contact 
for the galvanometer runs on the second dial and the other moving 
contact runs over a straight platinum-silver slide wire about 15 inches 
long, divided into 115 divisions, each of which corresponds to 0.01 
step on the second dial. The range of the potentiometer is thus from 
0 to 1.81 volts, one division on the slide wire being 0.0001 volt. By 
shifting a plug, the current through the dials may be reduced to 0.1 
the normal, lowering the range of the potentiometer in the same 
proportion. 

Mr. Tinsley has made a specialty of Weston normal cells, which he 
makes in accordance with the specifications of the British National 
Physical Laboratory. In this cell a constriction is made in the limbs 
of the glass H tube. The crystals become caked and the constriction 
holds them in place, so that the cells can be shipped without suffering 
damage. 

DRYSDALE WATTMETER. 

The Drysdale double wattmeter is constructed with the intention 
of avoiding all sources of error and of giving flexibility in use. It 
is a torsion-head instrument and contains 2 moving coils mechani¬ 
cally coupled and 2 sets of fixed coils. The latter are wound with a 
cable made of 10 insulated strands. By means of a commutator these 
strands may be joined in various groupings, so as to give the full 
ampere turns for 1, 0.5, 0.2, and 0.1 the maximum current. The up¬ 
per and lower systems are at right angles to each other to avoid 
mutual induction between them. The moving system is brought back 
to the zero position by turning the divided head, and in this position 
there is also no mutual inductance between the fixed coil and the 
moving coil of each system. Metal parts near the coils are avoided, 
the case of the instrument being of wood and glass, the screws and 
some other parts near the coils being made of ivoride. The 2 dyna¬ 
mometer systems may be used in series or in parallel on the same 
circuit or they may be used for the measurement of polyphase power. 
Single-phase power in one system may be balanced against direct- 
current power in the other, and various other special uses of the 
instrument are possible. The instrument is not astatic on direct 
current. The inductance of each moving coil is 1.5 millilienrys, and 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


47 


the normal resistance of the potential circuit is 5,000 ohms for 100 
volts, so that self-inductance errors are quite small at all ordinary 
frequencies. 

ALTERNATING-CURRENT POTENTIOMETER. 

The Drysdale alternating-current potentiometer consists of the 
combination of the Tinsley potentiometer for direct current, as above 
described, with accessory apparatus, namely, a Weston milliammeter 
of the electrodynamometer type, giving nearly full deflection for 50 
milliamperes, and a phase shifter. The latter resembles an induction 
motor, the wound rotor being adjustable in angular position over a 
range of 180°. For single-phase supply, the stator is wound as for a 
2-phase circuit, and a condenser is used to split the phase, and is 
adjusted so as to give a constant voltage in the rotor for any position 
of the latter. A pointer attached to the rotor has two scales, one 
reading in degrees of arc, the other in power factor. 

In use, the potentiometer is first supplied with a current of 50 
milliamperes from a storage cell, the current being adjusted in the 
usual way by reference to a standard cell. At the same time, the 
accuracy of the milliammeter in series with the potentiometer may be 
checked by taking the mean of two readings, the direction of the 
current through the milliammeter being reversed for the second read¬ 
ing. By a change-over switch, the potentiometer is now supplied with 
alternating current at 8 volts from the rotor of the phase shifter. This 
current is now brought to the same value (50 milliamperes) as deter¬ 
mined by the reading of the milliammeter. Unknown electromotive 
forces may now be measured by the potentiometer, using a vibration 
galvanometer as the detector. Balance requires two things, namely, 
that the unknown electromotive force has the same magnitude as that 
included between the two traveling contacts for the galvanometer, and 
also that the two electromotive forces are in the same phase. The 
two adjustments are made by successive approximations, and are not 
difficult to carry out. 

To secure accurate measurements with the alternating-current po¬ 
tentiometer it is necessary that the electromotive force of the supply 
circuit should approximate closely to a sinusoidal form. With such 
a supply the phase shifter is said to reproduce the primary wave form 
with the greatest harmonics due to distortion not exceeding 2 per cent, 
which introduces an error in the result which is practically negligible. 
The accuracy of the indications of the phase shifter is said to be 
within 0.1°. " This potentiometer has certain limitations, namely, the 
accuracy of the result can not be greater than the accuracy with which 
the milliammeter measures the current through the potentiometer; 
secondly, currents which are distorted in comparison with the electro¬ 
motive force causing them, such as the currents in circuits containing 
iron cores, can not be measured accurately. The reason for this latter 
condition is that the vibration galvanometer responds only to the sine 
component of the current through its coils, and hence if one attempts 
to measure, say, the current of a transformer whose secondary circuit 
is open, the reading of the potentiometer gives only the fundamental 
component of the magnetizing current, ignoring the large harmonics. 
In spite of these limitations, the alternating-current potentiometer is 
evidently a valuable research instrument for locating alternating 
currents and voltages, both in magnitude and phase, and it will 


48 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

doubtless prove useful for educational purposes also. It is said that 
the potentiometer works well up to 1,000 cycles or more, and is now 
being used for the investigation of telephonic currents. 

VIBRATION GALVANOMETER. 

The Drysdale-Tinsley vibration galvanometer has a small soft-iron 
vane suspended between the poles of a permanent magnet and carry¬ 
ing a small mirror. The magnetizing coils are interchangeable, and 
the tuning is accomplished by sliding a piece of soft iron along the 
limbs of the magnet, thus varying the amount of magnetic shunting, 
and hence the strength of the field in which the iron vane moves. 
This method of tuning does not cause shift of zero. 




FRANCE. 


J. CARPENTIER. 

The works of J. Carpentier, located at 20 Rue Delambre, Paris, 
produce a great variety of scientific apparatus, a large proportion 
of which consists of instruments for electrical and magnetic testing. 
In addition to resistance apparatus, inductances, condensers, galva¬ 
nometers, magnetic testing apparatus, and other instruments more 
especially for the laboratory, switchboard and portable electrical 
instruments are made. 

HOT-WIEE AND INTERCHANGEABLE-COIL WATTMETERS. 

The hot-wire wattmeter has two working wires joined in series and 
connected in parallel with a current shunt which is inserted in one 
line of the two-wire circuit in which the power is to be measured. 
The point of junction of the two hot wires is connected through a 
series resistance to the other line wire. The difference of expansion 
of the two wires is proportional to the power in the circuit. By 
means of a switch, the connections may be changed so that the in¬ 
strument reads volts; in a third position of the switch the current 
in amperes. 

The portable precision wattmeter has interchangeable series coils, 
each mounted in a wooden block that is guided accurately into place 
and held firmly. It is said that by care in the design and winding 
of these field coils the scale will be correct for each, and the reading 
multiplied by the constant of the series coil in use gives the watts. 
The series coils are made for currents from 1 to 300 amperes. The 
same instrument may be used as an ammeter. In this case the cur¬ 
rent to be measured is passed through the series coil and through 
a noninductive shunt. The small difference of potential at the termi¬ 
nals of this shunt is transformed up and applied to the moving-coil 
circuit. By using a series coil of fine wire connected in series with 
the moving coil and its series resistance, the instrument becomes a 
voltmeter. Current, voltage, and power can be read successively by 
means of a special switch. 

PHASE METER-AMMETER SHUNTS-OSCILLOGRAPH. 

The Arno phase meter consists of two dynamometer instruments 
in one case, with their needles crossing. One instrument measures 
the watts in a circuit, the other the volt amperes, and the intersection 
of the two gives the phase angle. 

Manganin is used as resistance material in ammeter shunts for 
switchboard and portable instruments. A convenient combination 

49 


65509°—13-4 



50 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


shunt is made for use with a portable millivoltmeter. This consists 
of four shunts in series, one line terminal and one millivoltmeter 
terminal being connected to one end of the series. To the other end 
is connected the other millivoltmeter terminal. The second line 
terminal is connected by a slider to the junction points of shunts 
1 and 2, 2 and 3, 3 and 4, or the end of shunt 4, thus changing from 
one range to another without opening the circuit or changing any 
connections. The general plan is that of the Ayrton-Mather uni¬ 
versal shunt for galvanometers. 

The Blondel oscillograph is made in two types, which differ only 
in the construction of the galvanometer. In one form the galva¬ 
nometer has fixed coils acting to deflect a small piece of iron carrying 
a light mirror; in the other a fine bronze loop is stretched in a mag¬ 
netic field and carries a mirror. 

PYROMETERS-MOVING-IRON INSTRUMENTS-FREQUENCY METER. 

Pyrometric apparatus is made on the thermoelectric and the re¬ 
sistance principle. Fery radiation pyrometers are also made. 
Moving-iron ammeters and voltmeters are made on the repulsion 
principle and have air damping. The Ferrie-Carpentier frequency 
meter consists of two hot-wire milliammeters. One of these in series 
with an inductive coil is paralleled with the other plus a noninductive 
coil; the parallel circuit so formed is connected in series with a 
resistance across the line whose frequency is to be measured. The 
frequency is read off from the point of crossing of the two pointers. 
The Ferrie-Carpentier ohmmeter is constructed on a similar plan. 
The Abraham frequency meter has a single system and pointer. 
A moving coil is pivoted in the field of an electromagnet, current 
being led into and out of the coil by silver strips of negligible torsion. 
A small noninductive resistance is in series with the electromagnet; 
the moving-coil circuit is connected to the ends of this resistance and 
includes the secondary of a small transformer, whose primary is in 
series with a high noninductive resistance. The electromotive force 
in the small resistance to which the moving coil is connected will 
decrease with increasing frequency, while at the same time the elec¬ 
tromotive force induced in the secondary of the transformer will 
increase. The moving coil will be traversed by a current whose mag¬ 
nitude and phase depend upon the resultant of the two electromotive 
forces, and the coil will take up a position varying with the fre¬ 
quency, but not with the voltage. The instrument has a very open 
scale, 2.5 cycles either way from the frequency corresponding to the 
central point (43 cycles) of a particular meter sending the needle to 
the end of the scale. 

COMPAGNIE ANONYME CONTINENTALE POUR LA FABRICATION DES 

COMPTEURS. 

The works of the Compagnie Anonyme Continentale pour la 
Fabrication des Compteurs are located at 9 Rue Petrelle, Paris. The 
company was formed in 1853 and for years made gas meters and 
water meters. With the rise of the electrical industry, the manufac¬ 
ture of electric meters was taken up in 1885. 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 51 
BUILDING AND EQUIPMENT. 

The building is three stories high and is built with a central court, 
which is roofed with glass. The heavy machines used for operations 
on castings for water meters and for punching sheet metal for gas 
meters are located on the ground floor of this court. The lighter 
machine work and the assembling and testing of electric meters are 
done on the upper floors, which are lighted by the court. The ma¬ 
chinery is group driven by 3-phase motors connected to the local 
supply mains. 

There is little or no American equipment in the w T orks. Turret 
lathes are used freely, on account of the large number of small parts 
required by electric and gas meters. Some of the machinery used for 
making gas-meter parts has been designed and built by the company; 
an instance of this is a machine for milling brass gear wheels. The 
blanks are assembled to a length of about 6 inches on a mandrel, 
which revolves under a rotating cutter, whose general form is that of 
a worm; the work is flooded with oil. While one set of blanks is 
being cut a second set is being strung on the mandrel and mounted 
ready to start under the cutter when the first set is finished. 

No female or child labor is employed, the reason being that women 
and children are not insurable against accident. 

DIRECT-CURRENT WATT-HOUR METERS. 

The “ Vulcan ” direct-current meter has been made by the company 
since 1898. In general principle it is the same as the Thomson meter. 
The commutator is placed at the top of the spindle and projects 
above the main cover of the meter. A small cap fits over the bracket 
supporting the shaft and the brushes, and may be sealed independ¬ 
ently of the case proper. Thus the lighting company may have 
access to the commutator for cleaning, maintaining its seals, while 
the municipal authorities in charge of meters may have their seal 
on the case as a whole. 1 A third seal at the bottom of the meter, 
also under the lighting company’s control, gives access only to the 
terminals and to the screw that enables the weight of the rotating 
element to be taken off the jewel when the meter is to be moved. 

The register is placed near the middle of the shaft, between the 
held coils and the damping device. The latter is not the familiar 
disk, but is a cylinder similar to the one used in the Fort Wayne 
type K induction meter. It differs from the latter in being greater 
in diameter, shorter in axial length, and in being made of copper. 
The cylinder is carried from the shaft by three light ribbed arms. 
The object of the construction is to avoid the dead material of the 
usual disk and to have all the metal passing through the air gap 
at one maximum linear velocity for a given number of revolutions 
per minute. The magnets are four in number and are placed as far 
as possible from the field coils. They are placed in such a position 
as to suffer the least change due to short-circuit currents in the field 
coils. The adjustment of full-load speed of the meter is made by 
screwing the copper cylinder up or down on the threaded spindle. 


1 This arrangement is said to be a legal requirement in Austria. 







52 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

The spindle is pivoted in a spring-supported sapphire jewel. The 
company has tried artificial ruby jewels as substitutes for sapphire; 
but while they are very hard, they have the drawback of greater 
brittleness, so that, on the whole, they are not preferable to sapphire. 

Constantan wire on porcelain spools is used tor the extra resistance 
in the armature circuit. This gives a higher temperature coefficient 
than would be desirable in meters for locations subject to wide varia¬ 
tions of temperature. As most meters are installed in dwellings, 
where the temperature does not vary widely, and as the legal require¬ 
ments here are not very rigorous in this particular, the company 
prefers to use constantan, to save space and cost. For cases where 
meters of low temperature coefficient are required it uses resistance 
coils of high temperature coefficient. 

The commutator is of silver, and each brush is made of a number 
of silver wires side by side. The normal full-load speed of the 
armature shaft is 60 revolutions per minute. The current in the 
armature is 22 milliamperes. 

COSINUS INDUCTION WATT-HOUR METERS. 

The company makes induction watt-hour meters under the trade 
name “ Cosinus.” These meters are similar to other induction meters, 
but have the distinguishing feature that no lag coil or loop is used 
to produce the adjustment for inductive loads. The rotating disk 
of an induction meter acts as a closed secondary for the potential 
flux and also for the main flux and gives a resultant potential flux 
and main flux, respectively. It is stated that the Cosinus meter 
has such an arrangement of the magnetic circuit that the reaction 
due to the disk gives the lag adjustment. A fine adjustment, how¬ 
ever, is provided by a screw that varies the width of an air gap in 
a leakage path. The disks are of copper, the jewels are sapphire, 
and the clock register is supplied in preference to the cyclometer 
form. The full-load speed is 60 revolutions per minute. 

DEPASSEMENT AV ATT-HOUR METERS. 

The “ depassement ” meters of the Compagnie Continentale are 
made in two types. In one of these an induction meter of regular 
construction runs at a speed proportional to the power taken by the 
customer. A second motor element runs at a constant speed, and is 
operated by the line current only. The meter spindle and the spindle 
of the constant-speed element are geared differentially to the register, 
so that the latter will totalize the difference of the revolutions of the 
two spindles. Furthermore, a ratchet is provided, so that the register 
can not be moved backward. Hence the register will record only Avhen 
the speed of the meter spindle exceeds the constant speed of the 
special motor element. The principle of the latter is of interest. If 
the voltage could be kept constant, an induction-meter element could 
be used, with a series coil of fine Avire connected (with a suitable non- 
inductive resistance) across the mains. However, the speed of such a 
motor would vary as the square of the voltage. For this reason an 
induction-meter element is used, in which both current and poten¬ 
tial cores are Avound with coarse Avire: the two Avindings are in par¬ 
allel, and the whole in series with the line. _ By suitable means a dis- 



ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 53 

placement of phase is produced, giving a driving torque. The 
counter torque is not supplied by a permanent magnet, but by a lami¬ 
nated electromagnet also in series with the line. Since both the driv¬ 
ing torque and the counter torque vary as the square of the current, 
the speed will be constant, if friction be neglected, for all values of 
the current. In practice, since the torque falls off as the square of the 
current, this form of depassement meter can not be used below one- 
third of full load. That is, a meter of 300 kilowatts capacity would 
be used where the agreed maximum (above which the meter is to 
register) is not less than 100 kilowatts. The normal speed of the 
“ constant-speed ” element can be varied by sliding the laminated 
brake magnet in or out radially, to vary its retarding torque for a 
given current. Thus, if the customer’s load increases, the limit above 
which he must pay an excess charge can be raised. 

To avoid the difficulties which would attend the construction of this 
type of meter in various current ranges, but one range is made, 
namely, 10 amperes; for other ranges, current transformers are used. 

The depassement meters are also made as two-rate meters with the 
same power limit for both rates, as two-rate meters with depasse¬ 
ment for one of the rates and total registration for the other, and as 
two-rate meters with different depassements for the two. 

As the preceding meters are expensive, their use is limited to the 
more important installations. To provide a less expensive depasse¬ 
ment meter for smaller installations, the Cie. Continentale makes 
another type, applicable only to noninductive loads. It is the same 
in general principle as an ordinary induction meter, but has two 
windings on the laminated core which ordinarily carries only the 
series winding. One is a series winding connected in the line as 
usual, the other a fine wire coil connected across the line in series 
with a high noninductive resistance. The ampere turns of the fine 
coil oppose those of the coarse coil, and hence with the current in the 
latter below the value giving equal and opposing ampere turns, the 
meter would run backward if it w T ere not for a ratchet which pre¬ 
vents backward motion. 

COMPAGNIE DE CONSTRUCTION ELECTRIRUE. 

The works of the Compagnie de Construction Electrique are located 
in Issy-les-Moulineaux, a suburb of Paris. The buildings are quite 
modern, having been erected in 1909. They are fireproof, one story 
high, and have the saw-tooth roof. The lighting is excellent, and 
ample room is provided for the work and for growth of the business. 

EQUIPMENT-LABOR. 

The machine tools are driven by line and counter shafting by a 
three-phase motor connected to the local supply mains, which also 
furnish current for meter testing. As a precaution against passible 
failure of supply, a gas engine is installed, direct-connected to an 
alternator which can supply current for operating the machinery 
and for the meter testing. 

American machine tools are better represented in this factory than 
in any other French factory visited by the writer. Among the tools 
noticed were a Bliss press, Warner & Swazey turret lathe, a Prentice 


54 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

three-spindle drill, and several other machines. When asked for his 
opinion of American machine tools, M. David, director of the com¬ 
pany, at once spoke of the accuracy of their construction. 

All work is done by men, no female labor being employed. The 
piecework system is largely used. The winding of potential coils of 
induction meters is accomplished at a very low cost, the company 
furnishing molded spools, wire, flexible terminal leads, and paper 
for covering the coil; each man then performs all the operations to 
produce the finished coil. The same idea is applied to the assem¬ 
bling; parts are served out in trays, each holding those needed for 
10 meters. Each workman assembles his own lot of meters, and is 
responsible for their condition when they come into the testing room. 
If any faults are found in a meter it is sent back to the man who 
assembled it, who must make it good on his own time. The advan¬ 
tages claimed for this system are that it puts much greater responsi¬ 
bility on each man, and also develops him into a more skillful work¬ 
man than he would be under the system of having each man perform 
but one operation. 

B T INDUCTION WATT-HOUR METERS. 

The company’s product is limited to induction watt-hour meters 
and their accessory apparatus, such as current and potential trans¬ 
formers. The meters are known by the trade designation “B T”; 
they were formerly known as the Batault meters. The line includes 
single-phase, two and three wire meters; polyphase meters for bal¬ 
anced and for unbalanced loads; three-phase four-wire meters; pre¬ 
payment, two-rate, and “ depassement ” meters. Standard current 
ranges include 2, 3, 5 . . . up to 300 amperes; the 3-ampere and 
5-ampere ranges are most in demand. 

While the general principle of the B T meter is that common to 
all induction meters, some points of design and construction are of 
interest. Copper disks are used, the company having given up the use 
of aluminum. Copper disks are preferred because their greater torque 
and greater inertia make the meter less sensitive to increase of fric¬ 
tion, due to the collection of dust on the disk or in the gearing. The 
complete moving system with copper disk weighs 55 grams. The 
company states that the wear on pivot and jewel, when copper disks 
are used, is not much greater than that with aluminum disks weigh¬ 
ing 20 grams; the torque with the copper disk is 80 to 100 millimeter- 
grams, as against 30 to 40 for usual meters having an aluminum disk. 
They state that the ratio of torque to weight, on Avhich stress is laid 
by some designers, is of little consequence, since the friction of the 
pivot and jewel is absolutely negligible in comparison with that 
of the gearing. The company furnishes regularly the clock dial; 
cyclometer dials are not recommended by it, but will be furnished 
on special order. 

The full-load adjustment is usually made (with the damping mag¬ 
nets fixed in the position for maximum drag) by screwing an iron 
bridge piece toward or from the laminated poles of the motor ele¬ 
ment, so as to vary the reluctance, and hence the driving torque. An 
adjustment of the drag magnets may be made if necessary. The 
light-load adjustment is made by a lateral micrometer adjustment 





ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 55 

of the iron bridge piece, so as to give a slight dissymmetry to the 
magnetic circuit. The lag adjustment is made by the vertical move¬ 
ment of a copper stamping, which has two rectangular openings, so 
that it can be slipped on the stampings bearing the shunt and series 
coils. This rectangle is slipped over the poles after all the coils are 
in place. Rectangles of various thicknesses are kept in stock to 
provide for various types of meters. The rectangle may be readily 
removed and replaced without disturbing any other part of the meter. 

The power loss in the potential coil and that in the series coil at 
full load are said to be less than 1 watt each. The meters up to 10 
amperes will start on 1 per cent; above 10 amperes, on 0.5 per cent 
of rated power. 

POLYPHASE, TWO-RATE, AND DEPASSEMENT METERS. 

In the company’s polyphase meter, two disks are used, each being 
acted on by a motor element and a drag magnet. The poles of the 
lower motor element point downward, and those of the upper element 
point upward, thus separating the working magnetic fields as far as 
possible to avoid interaction between the elements. It is claimed that 
this construction has been found so good that tests on polyphase and 
on single-phase current show no difference, thus permitting the use 
of the simple single-phase test with one wattmeter. 

The company’s two-rate meter has a motor element (or elements) 
as in the regular meters, but has two registers. One or the other of 
these registers is connected to the spindle by a. clock mechanism in a 
separate case. The meter and the clock are connected by three wires. 
This construction is preferred by the company to that in which clock 
mechanism and meter mechanism are contained in the same case. 

The “ depassement ” meter made by the company is identical in 
construction with the regular meter^ but has in addition a cylinder of 
nickel carried on the shaft and revolving in the field of a permanent 
magnet. The meter will not start until a certain specified load is 
exceeded, when it will run and register the excess above the specified 
load. The adjustment of the specified load is accomplished roughly 
by sliding the nickel cylinder on the shaft, so as to vary the amount 
of nickel in the field; finer adjustment is then made by means of a 
micrometer screw forming part of a magnetic shunt to the permanent 
magnet. 

The standard instruments used in the company’s testing room are 
Siemens & Halske & Cie. des Compteurs wattmeters. Test is made 
on actual load, using incandescent lamps. 

, The company obtains most of its supplies from French, Italian, 
and Spanish sources, and sells its product principally in France. 
It does not supply any meters to the United States. 

COMPAGNIE FAC. 

The Compagnie FAC, whose works are located at 81 Rue St. Maur, 
Paris, makes a large variety of switchboard and portable voltmeters, 
ammeters, and wattmeters. A conspicuous feature of the product is 
tfie low-priced small instrument, for the manufacture of which the 
company is specially well equipped. 


56 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


EQUIPMENT AND METHODS. 

The work is carried on in a building three stories high. A feature 
that attracts attention is the fact that each machine is driven by a 
small direct-current motor, usually attached to the ceiling. This 
reduces to a minimum the belting and shafting required, and thus 
gives better lighting and less dirt than the more usual arrangements. 
In circuit with each motor is a small ammeter^ located so as to be 
conveniently seen by the operator, who can thus tell at a glance 
whether the motor is carrying the usual load; in case of undue fric¬ 
tion or other difficulty, the trouble is known before it results seriously. 1 * * 
The company has striven to reduce the cost of its instruments, not by 
the use of inferior material, but by designs that eliminate as much 
as possible the work of assembly, even at the cost of very special 
fixtures and machines. This policy is possible in the manufacture of 
small indicating instruments, which are made by the thousands. 

The machines in use are mostly of French manufacture, a few 
only, including a three-spindle drill, being of American make. A 
small milling machine with three adjustable heads is used in milling 
the cases of “ watchcase ” pocket instruments. Much of the equip¬ 
ment suggests watch manufacture, on account of the small size of 
the springs, pivots, and other parts. The equipment, which is very 
complete, includes a plating department. The lighting of the works 
is very good, and the general arrangement is convenient. 

The company classes as “ precision ” apparatus only the perma¬ 
nent-magnet moving-coil type; it believes that moving-iron instru¬ 
ments can not be included under this head, and furnishes them as 
“ industrial ” instruments, which may, however, be had with “ pre¬ 
cision mounting, 5 ’ which includes the use of sapphire or ruby jewels. 

PRODUCTS-AIR-DAMPING. 

All instruments are of round pattern, with the exception of the 
twin ammeter-voltmeter for automobile use. Six diameters of scales 
are used, ranging from 60 to 250 millimeters (2.4 to 9.8 inches), and 
a large variety of cases are supplied. Damping may be applied to 
all moving-iron instruments except the smallest. Instruments hav¬ 
ing scales 80 millimeters (8.1 inches) in diameter have a damping 
vane attached to the index, moving in a sector-shaped damping com¬ 
partment, of which the scale plate forms the back and the cover 
glass the front. The vane is thus visible, and, in fact, the outer end 
of the vane serves as the pointer. For larger instruments a different 
arrangement is used. Two square pistons, attached by light stamped 
arms to the moving system, move in two annular chambers in a 
circular metal box, which is concentric with the moving system. As 
the latter moves, one piston compresses the air in its chamber, while 
the other one rarefies it; this arrangement is said to give uniform 
damping for all parts of the travel of the moving system. This 
damping arrangement is also applied to the largest permanent-mag¬ 
net moving-coil instrument, in which the high moment of inertia 
of the long index makes it difficult to get sufficient damping bv 
Foucault currents in the coil frame. 


1 In the writer’s opinion, there is a large field for the use of small, cheap, well-made 

instruments in connection with motor drive. This field could be developed by educating 

the motor users. 



ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 57 


WATTMETERS—FLUSH INSTRUMENTS. 

The company makes wattmeters on the electrodynamometer prin¬ 
ciple in four sizes; the smallest has a scale of 80 millimeters (3.1 
inches) in diameter. This is the smallest wattmeter the writer has 
seen. It has the air-damping arrangement above described for 80- 
millimeter instruments, and is not made for currents above 15 
amperes. The price is moderate—$7.95. 

Four sizes of instrument are made in flush pattern; the smaller 
sizes make a very neat appearance on small switch panels for accu¬ 
mulator charging, electromedical purposes, etc. The smaller flush 
pattern instruments are also mounted, singly or in pairs, on finished 
wooden bases. These bases may have covers hinged to them to 
protect the instruments, or a carrying box may be supplied for the 
same purpose. Both arrangements are neat and attractive, and the 
prices are moderate; they should have a large sale to amateurs and 
others who need to make measurements of moderate accuracy. The 
company also supplies its precision direct-current instruments in • 
similar mountings, for more accurate work. 

LAMP-TESTING AND AUTOMOBILE INSTRUMENTS. 

Combined volt and ampere meters are made in a large number of 
styles, chiefly for use in battery testing. For testing incandescent 
lamps three types of instruments are supplied, nam'ely, ammeter 
only, ammeter and voltmeter (separate movements) in one case, and 
wattmeter. 

For automobile use, the company makes small flush-pattern am¬ 
meters and voltmeters with square flush plates of finished brass. 
These plates are similar in style and size to the plates used in the 
United States with flush switches. Single instruments are furnished 
in this style, also wider plates containing ammeter and voltmeter 
side by side. 

Other products of the company include battery charging panels, 
polarity indicators, insulation testers, pyrometric apparatus, and a 
magnetoscope. The last is a simple device for measuring the relative 
strengths of magnets of a given form. It is easily and quickly 
operated, and is low in price—$2.32. 

The company has in course of development a line of hot-wire in¬ 
struments; also a line of registering instruments, and at present 
constructs some of these on special order. 

COMPAGNIE POUR LA FABRICATION DES COMPTEURS ET MATERIEL 
D’USINES A GAZ. 

The electrical works of the Compagnie pour la Fabrication des 
Compteurs et Materiel d’Usines a Gaz are located at 16 and 18 
Boulevard de Vaugirard, Paris. The company made gas and water 
meters years before the electrical industry was in existence; it has 
made electric meters from the beginning of the use of such meters. 
It is now making about 400 electric and 200 water meters per day, 
in addition to gas meters. The latter are made in two other factories 
in another part of the city. 


58 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


EQUIPMENT-LABOR. 

The works are extensive and provide for practically all the opera¬ 
tions required in meter manufacture. A foundry on the ground floor 
produces brass and aluminum castings; iron castings for electric and 
water meters are purchased from outside foundries. Much of the 
machinery is special, and little is of American manufacture. One 
American machine noticed was a heavy turret lathe for finishing the 
interior of brass water meters, which require very accurate work¬ 
manship. In the coil-winding department are a number of special 
machines, one of which winds six coils at once. For doing “ univer¬ 
sal ” winding two types of machine are in use. The more recent one 
is said to do the work as well and as rapidly as the other, and the 
cost was only a fraction of that of the other. 

There is an absence of the female labor so common in American 
meter and instrument factories. Men do the winding of coils, for 
which female labor is usually considered to be well adapted. The 
• local regulations do not allow women and children to work as many 
hours a day as the men, and employers can insure only men against 
accidents. 

ASTATIC DIRECT-CURRENT WATT-HOUR METERS. 

The electric product of the company includes both integrating and 
indicating apparatus. Their model B watt-hour meter 1 is con¬ 
structed on the general principle of the Thomson “recording watt¬ 
meter,” but has a flat disk armature composed of three form-wound 
coils incased in insulating material. This type of armature has the 
great advantage of being astatic to uniform stray fields. The drag 
magnets are at the top of the spindle, the armature and commutator 
at the bottom. The register is placed in the middle and has six dials, 
the upper four being the ones usually read and recorded, and having 
black figures on a wdiite ground. The two lower dials have white 
figures on a black ground and red pointers; the lowest dial has 100 
divisions. These lower dials are for greater convenience in testing 
the meter as a whole, including the gearing ratio. The drag magnets 
are held in a fixed position and an iron bridge piece near the poles has 
two iron screws which can be adjusted so as to vary the flux shunted 
from the njagnet, and hence the flux through the drag disk, which is 
made of aluminum. The brushes can be turned slightly on the holder, 
withdrawn, and afterwards replaced in the same position with the 
original tension; the latter can be adjusted by a set screw. The meter 
is said to start at 0.5 per cent of rated load and to have a maximum 
error of 3 per cent at 5 per cent of rated load. 

Model B meters are also made for switchboard service, up to 2,000 
amperes two-wire or 1,000 amperes three-wire, with the entire current 
passing through the series coil; above these values a shunted meter 
is used. In the latter the current through the meter (with rated load 
in the line) is 50 amperes, and the drop at the shunt terminals is 300 
millivolts. 


1 Within the last few years meter makers in the United States have been urged to use 
the expression “ watthour meter ” in place of the much used but incorrect terms “ record¬ 
ing wattmeter ” and “ integrating wattmeter.” and the term “ watthour meter ” is comin^ 
into use. Some objection has been raised to the use of “ watthour ” as one word bv 
those who prefer the form *• watt-hour.” Tt is therefore interesting to note that the 
French company here referred to goes so far as to use “ wattheuremetre ” as a single 

worn 





ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 59 

\ 

FIVE-WIRE DIRECT-CURRENT WATT-HOUR METERS. 

In addition to the two-wire and three-wire arrangements well 
known in the United States, model B meters are also made for five- 
wire circuits. The five-wire system is used to some extent abroad, to 
save copper; it has never been favorably considered in America. It 
has three “ neutral ” wires, which carry only the unbalanced cur¬ 
rents, and hence need not be so large as the two “ outers.” In the 
model B five-wire meter there are two field coils above the armature, 
one in each outer, of wire or strap heavy enough to carry the rated 
current in the outer. Below the armature are two field coils of 
half the number of turns of the others, inserted in the two neutrals 
next to the outers. The third central neutral is attached to a binding 
post of the meter (but has no series coil) in capacities up to 75 
amperes; from 100 amperes up, the central neutral wire does not 
enter the meter. 

The company’s type A, an older form, is similar to the classical 
Thomson meter, but has the commutator at the bottom of the shaft 
and the register at the top, with the drag disk immediately below. It 
is stated that the construction is such that the meter can be used 
equally well on direct current or on alternating, including inductive 
loads. 

INDUCTION WATT-HOUR METERS. 

The company’s induction watt-hour meter, model A. C. T. Ill, is 
made with one motor element for single-phase two-wire and three- 
wire or three-phase balanced circuits; with two motor elements acting 
on one disk for unbalanced three-phase three-wire or two-phase three- 
wire or four-wire circuits; and with three motor elements for three- 
phase four-w T ire circuits. For this latter use they do not consider the 
meter with two motor elements accurate enough, since this meter 
is accurate only when the three voltages are equal and their phase 
relation to each other is symmetrical. Their three-element meter has 
a longer shaft than the other forms, with one disk at the bottom acted 
on by two motor elements, and another disk at the top acted on by 
the third motor element and the drag magnet. Their meter for two- 
phase five-wire circuits has two motor elements wound as for single¬ 
phase three-wire circuits, acting on one disk. 

The shunt-coil loss of A. C. T. Ill meters is given as 0.9 watt per 
element and the starting load as 0.5 per cent of the rated load. The 
lag adjustment is made by a copper U-shaped strap which surrounds 
the potential core; the ends of the U are joined by a screw whose 
length is about twice the distance across the top of the U, and which 
is of copper for half of its length and resistance alloy for the other 
half. By turning this screw, the resistance of the loop circuit can be 
continuously varied until the desired lag adjustment is secured, when 
the screw contacts may be made secure by tightening locknuts on the 
screw against the copper loop. The armature is of aluminum, and 
the torque is about 25 millimeter-grams for one motor element, or 45 
for two elements. The aluminum disk is used with the clock form of 
register, which the company prefers to supply. 1 On special order 
they supply induction meters with cyclometer dials, but in this case 
they prefer to use copper disks, partly to increase the torque to over- 


i This does not apply to tramcar meters, for which cyclometer dials are standard. 



60 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

come the extra friction and also to increase the moment of inertia, 
to enable the rotating element to overcome extra friction occurring 
momentarily, such as might occur at the moment when several 
wheels of the dial were to be turned at once. 


AMPERE-HOUR METERS. 

The “ O’K ” ampere-hour meter, made by the Compagnie des 
Compteurs, has been extensively used, as about 300,000 have been 
manufactured. It is a motor meter, with a strong permanent magnet 
between whose poles rotates a drum armature without iron, having 
form-wound coils, which is in parallel with a manganin shunt con¬ 
nected in one of the line wires. The commutator segments and the 
brushes are of gold, and the diameter of the commutator is small, 
namely, 3 millimeters (0.12 inch). There is no damping device; the 

armature being connected 


to the terminals of a shunt 
in one of the lines, runs at 
a speed practically propor¬ 
tional to the drop on the 
shunt. In the smaller sizes, 
the rate of the meter (at 
full load) is adjusted by 
varying' the resistance of 
the shunt. In larger sizes, 
where this would be incon¬ 
venient, a magnetic shunt 
is varied. 

Below 15 amperes the 
O’K meters are not com¬ 
pounded ; for 15 amperes 
and above, a current of 
about 0.01 ampere is taken from the line to provide an initial starting 
torque. The three-wire O’K meter has two armatures which are 
magnetically in series between the poles of the magnet. The revolu¬ 
tions of the two armatures are totalized on one register. 



Fig. 2.—Diagram of circuits, O’K watt-hour meter. 


WATT-HOUR METER WITH STIUNTELET. 


The preceding O’K meters are marked to read in hectowatt-hours 
or kilowatt-hours, on the assumption that a certain nominal voltage 
is maintained at the consumer’s premises. An interesting variation is 
the O’K watt-hour meter with “ shuntelet,” which is an O’K ampere- 
hour meter provided with an additional device which causes the 
registration to be proportional to the watt-hours, for voltages within 
10 per cent of the normal. The operation of this meter may be seen 
from figure 2. A shunt AB is in series with one line wire, and the 
two resistances r x r 2 , which have a high temperature coefficient, are 
connected in series with each other and across the shunt. The arma¬ 
ture I is connected between the junction C and the adjustable point D. 
Around the resistance r 2 is wound a fine-wire heating coil R, which is 
connected across the mains. As the voltage varies, the resistance r 2 
varies, and by shifting the contact D, the speed of the armature may 
be made to vary as the watts, within the stated limits (±10 per cent). 
A thermocouple heated by the heating coil supplies a current which 











ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 61 

o\ercomes the friction torque at light load. The remaining adjust¬ 
ment, namely, the full-load speed, is made by a magnetic shunt. The 
power taken by the heating coil is said to be from 3 to 4 watts. 

SPECIAL AMPERE-HOUR METERS. 

Another variation of the simple O’K ampere-hour meter has a vari¬ 
able magnetic shunt, which is graduated in terms of voltage, the 
range being from 10 per cent below to 10 per cent above a normal 
value. This meter may thus be adjusted at the point of use to read 
watt-hours, for any voltage within the above limits. 

The O’K ampere-hour meter is also made for battery charging. In 
this form, a special register may be supplied, having a dial of large 
diameter. One revolution of the index of this dial corresponds to A 



Pig. 3.—Diagram of connections, O’K ampere-hour meter for 
storage-battery use, with “ efficiency ” shunt. 


quantity somewhat greater than the maximum charge. This dial 
shows the state of the battery; three additional dials of the usual 
diameter are provided to totalize the successive discharges. Another 
arrangement is shown in figure 3. The meter is connected across the 
ends of a shunt BA having a central connection C which is adjust¬ 
able. The point C should be shown nearer to A, for the practical 
case, since the ratio BC-kBA should be adjusted to equal the ampere- 
hour efficiency of the battery. When the battery is being charged, 
the drop of potential at the meter terminals ef (for a given current) 
is proportional to BC; on discharge, the drop for the same current is 
proportional to BA. Hence the meter will run faster on the same 
current when discharging, and its reading at any time shows the 
charge remaining in the battery. Contacts may be provided, so 
































62 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


that the bell S will be rung at the end of charge or discharge. Other 
special arrangements of O’K meters are made to meet special re¬ 
quirements in battery work. For electrolytic work, the O’K meter is 
provided with two dials—one of the usual form, to totalize the 
amount of metal deposited, and a dial of larger diameter which can 
be used to determine the amount of metal for each operation. Both 
dials are graduated in grams or multiples of grams. 

DEPASSEMENT, TWO-RATE, AND VARIABLE-RATE METERS. 

The “ depassement ” meter of the Cie. des Compteurs is of the type 
in which a meter of regular form (A. C. T., B, or O’K) is provided 
with a cylinder of nickel carried by the spindle and revolving be¬ 
tween the poles of an auxiliary permanent magnet. The torque due 
to hysteresis in the nickel will be constant for all speeds (neglecting 
eddy currents), and hence the meter will turn only when the load 
exceeds a given maximum, and its speed of revolution at any moment 
will correspond to the excess power. 

The two-rate meters of the Cie. des Compteurs contain a regular 
meter of suitable type and a clock mechanism, both in one case. The 
clock mechanism is supplied either for hand or electric winding. 
Multi-rate meters are also made which allow four rates of charge in 
the 24 hours. 

The company also supplies meters with the Mahl variable-rate sys¬ 
tem. The object of this system is to vary the rate throughout the 24 
hours of the day, charging the lowest price when the station load is 
lowest, and vice versa. These meters have two dials; one showing 
the total ampere-hours or hectowatt-hours used, and the other the 
total in monetary units (francs). The variation of the rate is accom¬ 
plished by a special mechanism interposed between the rotating 
spindle and the monetary dial. This mechanism contains a cam, 
whose profile is shaped as desired, in accordance with the load curve 
of the particular station. A pointer attached to the mechanism 
moves over a scale and shows the rate in force at any moment. 

TRAMWAY AMPERE-HOUR METER. 

Other special meters are made, including prepayment and tramway 
forms. The latter is the O’K ampere-hour type, with the meter ele¬ 
ment suspended by a spring inside an iron case. For this meter the 
company supplies the simple cyclometer dial, which is preferred be¬ 
cause it can be read by unskilled men; the motorman should be able 
to check his own use of current. Further, there is no light-load 
problem with tramcar meters, so the extra friction of the cyclometer 
dial is not a serious matter. The saving of current due to. the use 
of tramcar meters was estimated by M. Delalandre, of the Cie. des 
Compteurs, as about 12' per cent. This estimate is said to be borne 
out by the experience of several Paris electric railways. 

FRICTION NEUTRALIZER FOR WATT-HOUR METERS. 

In order to minimize the effect of friction on light-load accuracy, 
especially in commutator meters, the company applies (on special 
order) a device called a “ demarreur.” This is a small motor which 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 63 

runs constantly, being connected across the line. The motor is geared 
to a shaft carrying an eccentric, which is connected to the brush- 
holder yoke. The brushes are thus rocked back and forth through a 
small angle, the peripheral speed at the commutator surface being 
greater than the maximum peripheral speed the commutator would 
have with respect to a stationary brush. The starting friction is 
thus eliminated, and it is said that a meter so equipped will start at 
0.2 per cent of full load and will be accurate at 0.5 per cent load. 
The use of the demarreur is limited to large and important meters, 
such as the totalizing meters of central stations, which run at very 
low loads for some parts of the 24 hours. The power required by the 
demarreur is small—about 2.5 watts per 100 volts. 

DIRECT-CURRENT AMMETERS AND VOLTMETERS. 

The direct-current ammeters and voltmeters of the Cie. des Comp- 
teurs (“ System Mevlan d’Arsonval ”) have a coil wound on a copper 
or aluminum damping frame which is eccentrically pivoted, so that 
one side of the coil passes through the single air gap in the magnetic 
circuit. The construction is such that the coil can be put in place or 
removed without disturbing the magnetic circuit. The air gap is 
about 2 millimeters (0.08 inch), and the field strength is given as 
1,200 to 1,400 gausses. The sapphire jewels are spring supported. 
The cases are sector shaped to give the least area occupied for a 
given length of scale. Six models are made, with scale lengths rang¬ 
ing from 60 to 330 millimeters (2.4 to 13 inches). The design is such 
that the motion of the index is slightly underdamped; the company 
considers this better than critical damping, which gives room for the 
suspicion that friction is present. Voltmeters take less than 0.02 
ampere, and the scales are so divided that each division represents 
1, 2, 5, or 10 volts. Ammeters have interchangeable shunts, with the 
standard drop of 100 millivolts. The shunts are designed to give 
not over 150° C. rise of temperature at full load, though it is said 
that they will stand 300° C. without injury. In the case of large 
shunts, where it is necessary to keep down the power lost in the 
shunt, and where the temperature coefficient of the instrument is not 
important, the shunts are made for 60 millivolts drop. 

When direct-current voltmeters are desired with large divisions in 
the vicinity of the working point the company can meet the require¬ 
ment in two ways. In the first, a special shape is given to the magnet 
poles; this increases the length of a division near the working point 
to two or three times the length of a division on a uniform scale of 
the same length, and gives the advantage that the zero is on the 
scale; hence, changes or zero reading from any cause can be detected. 
The other plan is the “ suppressed-zero ” method, in which an initial 
tension is given to the springs. This increases the division length 
to four or five times the normal, but has the disadvantage that the 
zero reading is off the scale. 

MOVING-IRON INSTRUMENTS. 

Moving-iron switchboard instruments are made in four sizes. 
They are supplied for direct current when a low-priced instrument is 
required. For this use the calibration is made with direct current, 


64 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


and the + terminal is marked in order that the polarity may be 
made the same in use as in calibration. The voltmeters require 2.5 
to 5 watts per 100 volts. All sizes have air damping. Ammeters are 
made self-contained up to 1,500 amperes; for ranges from, say, 800 
to 1,500 amperes the company asks the customer to indicate the 
manner in which the conductors will be run to the instrument so 
that the factory calibration may be made under the same conditions 
of stray field. For large currents, or for use on high-voltage cir¬ 
cuits, ammeters are also supplied with current transformers. The 
secondary current is 2 amperes for transformers of only approximate 
ratio, the transformer and ammeter being calibrated together as a 
unit, or 10 amperes, for transformers adjusted to a definite value of 
ratio. 


HOT-WIRE AND ELECTRODYNAMOMETER INSTRUMENTS. 

Hot-wire instruments are made in two sizes, in cases uniform with 
the preceding. The hot wire in the voltmeter is surrounded by a 
closely wound spiral of fine enamel-insulated wire in series with the 
working wire, which latter is thus thermally shielded, reducing the 
radiation from it, and therefore reducing the power spent in the 
instrument. 

Electrodynamometer wattmeters are made in three sizes, uniform 
in style with the preceding. To keep the drilling plan the same as 
for other instruments of the same size, the current-terminal studs are 
bored out and the potential studs are passed through them. Induc¬ 
tion wattmeters are made in horizontal edgewise form, with glass 
case. To overcome the large temperature coefficient of this type of 
wattmeter, the magnetic circuit contains small bridge pieces of Guil¬ 
laume nickel-steel alloy, of which the permeability varies with the 
temperature. 

FRAGER LAGGING DEVICE-SHUNTED WATTMETER. 

The company makes accessory apparatus for the foregoing, includ¬ 
ing current and potential transformers. Synchronism indicators, 
phase meters, and registering instruments are also made, the last 
named in a large number of types. Space permits the mention of 
only a few points in regard to them. Registering wattmeters on the 
electrodynamometer principle are “ lagged ” to be correct on alter¬ 
nating current by the device of M. Frager. This consists of a short- 
circuited coil placed within the series coil. The combination of the 
flux due to the main current and that in the closed lag coil gives a 
resultant flux, which lags behind the main current. By proper"choice 
(or adjustment) of the lag coil this angle of lag may be made equal 
to the angle of lag in the potential circuit. The principle is similar 
to that of the lag coil in induction watt-hour meters. The shunted 
registering wattmeter was devised by M. E. Grassot. In general 
structure it resembles a permanent-magnet moving-coil instrument. 
The field magnet is of special soft steel of low hysteresis and is wound 
with fine wire, which is connected, with added resistance of low 
temperature coefficient, across the mains. The moving coil is of 
coarser wire and is connected, with some added resistance, to the 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 65 

terminals of a shunt, which may also be used to operate other instru¬ 
ments. The moving-coil circuit is said to be almost completely com¬ 
pensated for temperature; it takes less than 1 ampere at full load, 
the drop at the shunt terminals being then 300 millivolts, the same 
as for the company’s shunts for hot-wire ammeters. The shunted 
wattmeter may be used on a three-wire installation; in this case a 
double shunt may be used having three brass blocks and two sets of 
alloy strips. The positive generators have their neutral terminals 
joined to one end of the double shunt, the negative generators simi¬ 
larly to the other end, and the neutral line wire starts from the center 
block of the double shunt. 

PORTABLE INSTRUMENTS-THE ONDOGRAPH. 

Portable voltmeters, ammeters, and wattmeters are made on the 
same general plan as the switchboard instruments previously de¬ 
scribed. Portable direct-current millivoltmeters are regularly of 
2 ohms resistance and give full deflection for 100 millivolts. The 
temperature coefficient is 0.1 per cent per degree Centigrade. This 
may be compensated, if so ordered, by the use of a nickel-steel mag¬ 
netic shunt to the permanent magnet. This latter construction is 
regularly used in the precision portable millivoltmeters made by the 
company. The precision electrodynamometer voltmeter is supplied 
in an astatic type, when required. This makes the instrument inde¬ 
pendent of (uniform) stray fields and obviates the necessity for tak¬ 
ing the mean of two readings with opposite directions of the current 
when checking or using the voltmeter on direct current. 

The Hospitalier ondograph is an instrument for tracing alternat¬ 
ing-current wave forms. A small synchronous motor is geared to a 
rotating commutator and also to a drum bearing a paper chart. The 
gearing ratios are such that while the motor makes 1,000 revolutions, 
the commutator makes 999, and the drum one-third of a revolution. 
A permanent-magnet moving-coil galvanometer, specially designed 
for high torque and aperiodic motion, moves a pen over the paper 
chart, the motion of the pen, at the middle point of its travel, being 
at right angles to the motion of the paper. The commutator is ar¬ 
ranged to connect a condenser momentarily to the line whose voltage 
is to be traced; at this moment the galvanometer circuit is open. 
During the rest of the revolution of the commutator the condenser 
discharges through the galvanometer. The effect is practically to 
cause the galvanometer to follow the variations of the wave form at 
0.001 of the actual frequency; thus on a 60-cycle circuit, a complete 
period is traced in 16.25 seconds. 

THE GRASSOT FLUXMETER. 

The Grassot fluxmeter may be termed an industrial ballistic galva¬ 
nometer. It is made in a form similar to the company’s direct-cur¬ 
rent voltmeters, but has the moving coil suspended on a silk fiber, 
connection being made by means of very fine silver strips, to give the 
smallest possible torsion. The throw of the coil is read by an index 
and scale, and may also be observed by optical methods, as a mirror 

65509°—13 - 5 


66 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


is carried by the coil. In connection with small search coils whose 
number of turns and area are known, it may be used for magnetic 
measurements. Other applications of the instrument will suggest 
themselves to those who are familiar with ballistic methods. 

Pyrometric apparatus forms an important part of the company’s 
product, including thermocouple pyrometers and various types of 
Fery radiation pyrometers, the latter being made for temperatures 
up to 3,500° C. 

MAISON GRAINDORGE. 

The firm of Graindorge, located at 4 Rue de Borrego, Paris, manu¬ 
factures moving-coil and moving-iron ammeters and voltmeters in a 
large number of sizes. Special attention is paid to the construction 
of small low-priced moving-iron instruments, of which the firm sells 
a very large number. In these instruments the scale plate forms one 
head of the spool on which the actuating coil is wound. A brass 
tube carries the fixed piece of iron and contains the bearings for the 
shaft on which the moving iron and the pointer are carried. These 
brass tubes with shaft, etc., are made in quantity, all alike for all 
ranges of ammeters and voltmeters, and they and the wound bobbins 
are carried in stock. As instruments are required to fill orders, the 
proper capacity bobbins are selected and into each is inserted a brass 
tube carrying the iron system. The tube is held in position by 
cement. In spite of the low price of these instruments, a scale is 
made by hand for each one. As a further illustration of the care 
used, the silk-covered wire used for voltmeters is dried and paraffined 
before use. 

The low price at which these instruments are sold requires econom¬ 
ical design as well as manufacture in quantity, with every possible 
effort to reduce cost. One way in which costs are reduced is by allow¬ 
ing a considerable amount of routine work, such as coil winding, to 
be done at the homes of the workmen. 

Regular workmen employed in this factory earn 10 to 12 francs 
($1.93 to $2.32) per day of 10 hours, while apprentices earn 7 to 8 
francs ($1.35 to $1.54) per day. 

The small ammeters and voltmeters above referred to are also made 
as incandescent lamp testers, either with ammeter alone or ammeter 
and voltmeter combined in one case. 

JULES RICHARD. 

The works of Jules Richard are located at 25 Rue Melingue, Paris. 
The product includes a great variety of registering instruments for 
meteorological and other scientific purposes. Over 800 varieties of 
registering instruments are made, of which over 40,000 have been sold. 
Specially graduated and figured paper is carried in stock for all the 
800 varieties. 

The buildings are of brick, of modern design, well arranged, and 
with good lighting. A 50-horsepower steam engine is direct-con¬ 
nected to a generator for the power circuit, and is also belted to a 
countershaft in the room above, where are located special dynamos 
for testing purposes. No American machinery is used, the reason 
given being that they do practically no automatic work, all their 
apparatus being accurately made by hand. 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 67 


MOVING-COIL INSTRUMENTS-DOUBLE-SENSIBILITY AMMETER. 

Permanent-magnet moving-coil instruments have a small iron rider 
that bridges across the pole pieces and thus diverts some of the flux 
from the moving coil. It is claimed that this increases the per¬ 
manency of the magnet, and further, that by moving this rider to the 
proper position on the poles, as found by trial, the distribution of the 
useful flux can be modified so as to correct the scale for any small 
errors. 

An interesting modification of the usual moving-coil ammeter for 
direct current is the “ ammeter with automatic double sensibility.” 
In this ammeter the moving coil is controlled by the usual two spiral 
springs over, say, the lower two-thirds of the scale. When the coil 
moves farther, a third spring also opposes the motion, and thus the 
current required for a given increment of angular deflection is in¬ 
creased. For example, the lower two-thirds of the scale may be 
graduated from 0 to 100 amperes, while the upper third extends from 
100 to 300 amperes. This type of ammeter is intended for observing 
the running current of motors on the lower two-thirds of the scale 
and the heavy momentary starting currents on the upper third. It 
may also be used for observing the behavior of constant-potential 
arc lamps, which take currents much heavier than normal at start¬ 
ing, or when the carbons happen to come together. If an ammeter 
of the usual construction is used for these purposes, the angular de¬ 
flection given by the normal current is too small for accurate reading. 

The Richard registering electrical instruments include a hot-wire 
voltmeter, moving-coil and moving-iron ammeters and voltmeters, 
and dynamometer wattmeters. 


GERMANY. 


ALLGEME1XE ELEKTRICITATS-GESELLSCHAFT. 

The Allgemeine Elektricitats-Gesellschaft of Berlin is a large 
manufacturer of electrical apparatus and machinery. The present 
description is limited to electric meters, of which the company makes 
a large number. 

DIRECT-CURRENT METERS. 

Direct-current watt-hour meters are made in two general types, 
of which the first is a rotating meter on the Thomson principle. The 
lower bearing is of sapphire; the end of the shaft is hollowed out and 
rests on a polished steel ball. The bearing is filled with oil. This 
bearing is used in all A. E. G. meters. The following figures are 
given by the maker for the above type: Direct-current motor meters, 
up to 100 amperes—full-load torque, 65 millimeter-grams; weight 
of moving element, 125 grams; potential-coil loss (for 100 volts), 1.5 
watts; series-coil loss at full load, 10 to 14 watts; full-load speed, 80 
r. p. m. Direct-current motor meters, 150 to 1,000 amperes—full¬ 
load torque, 120 millimeter-grams; weight of moving element, 140 
grams; potential-coil loss (for 100 volts), 1.5 watts; series-coil loss at 
full load, 15 to 30 watts; full-load speed, 60 to 80 r. p. m. 

The second general type of watt-hour meter is the oscillating meter, 
which has not been used in the United States. The general construc¬ 
tion of this meter is very similar to that of the first type above men¬ 
tioned, except as to the moving element. This consists of a single rec¬ 
tangular coil of fine wire carried by a shaft, which also carries an 
aluminum damping disk. No commutator is used; current is led into 
and out of the coil bv two fine silver spirals in the axis of rotation. 
The motion of the coil is limited by two stops carrying electrical con¬ 
tacts. When a contact arm on the shaft of the moving element 
touches one of the stop contacts, the circuit of a relay is closed, and 
the relay operates a switch, reversing the current through the mov¬ 
ing coil and causing it to move toward the other fixed stop, when 
the current is again reversed, and so on. Each time that the relay 
operates it advances a ratchet wheel on the register one tooth. Thus 
the work of driving the register is performed by the relay, instead of 
by the moving element as in most meters. The friction of the usual 
commutator is also absent in the oscillating meter, the only source 
of friction being the bearings. To make the operation of the contacts 
more reliable, the circuits are so arranged that when contact is about 
to be made the voltage between the contact points is high, about 80 
volts, thus assuring the closing of the circuit. The reversal of the cir¬ 
cuit by the relay alters the connections in such a way that the voltage 
across the contact points at break is only two or three volts. The use 
of the ball bearing as previously described enables the meter to be 


68 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 69 

shipped or carried about without raising the moving system off the 
jewel bearing. The adjustment of the rate of the meter is made by 
varying the position of the stops, and thus changing the amplitude of 
the oscillations. The following figures are given for this type by the 
maker: Direct-current oscillating meters, 3 to 100 amperes—weight 
of moving element, 60 grams'; potential-coil loss (for 100 volts), 1.4 
watts; series-coil loss at full load, 5 to 10 watts; swings per minute, 
60. Direct-current oscillating meters, astatic type, 150 to 10,000 am¬ 
peres—weight of moving element, 75 to 151 grams; potential-coil loss 
(for 100 volts), 1.4 watts; series-coil loss at full load, 18 to 140 watts; 
swings per minute, 60. The potential-coil losses include the loss in 
the relay circuit. 

In sizes up to and including 30 amperes, the list prices of oscillat¬ 
ing meters are very slightly higher than those of the corresponding 
sizes of rotating meters; for 50 amperes and above, the prices of 
oscillating meters are appreciably higher, the 200-ampere oscillating 
meter listing about a third more than the same size rotating meter. 
The relay arrangement of the oscillating meter makes it possible to 
operate extra registers at a distance, which is often convenient for 
switchboard meters. 


AMPERE-HOUR METERS. 

The A. E. G. ampere-hour meter has a strong permanent magnet, 
between whose poles rotates an inverted copper cup with three fine- 
wire coils covering its outer surface. Inside the cup, but not touch¬ 
ing it, is supported an iron core. The commutator is of silver, and 
has three segments. The armature circuit is connected to the termi¬ 
nals of a shunt. The full-load torque is given as 150 millimeter- 
grams, with a drop of potential in the shunt of one volt. A three- 
wire ampere-hour meter is made by placing two sets of armature 
windings on the copper cup, the two being well insulated from each 
other by micanite, and connected to two commutators, one at each 
end of the shaft. 

A modified form of ampere-hour meter differs from the preceding 
in having spirally twisted commutator segments and an arrangement 
for moving the brushes up the commutator as the load increases. 
A coil is attached to the brush holder, and is connected in series 
with the armature. This coil is arranged to move over a projecting 
piece of iron attached to one of the pole pieces of the magnet as the 
current in it' increases. The movement of the brushes up and down 
the commutator is said to assist materially in keeping the commu¬ 
tator clean, and the spiral twist of the commutator is arranged so 
that the torque per ampere is greater at light loads, thus tending 
to overcome the light-load friction. These meters are said to be 
correct within 2.5 per cent from to fhll load. The type without 
the above special feature is said to have the same error limit between 
and full load. 

INDUCTION WATT-HOUR METERS. 

The A. E. G. induction watt-hour meter does not differ appreci¬ 
ably in general construction from those made in the United States. 
The magnetic system consists of an I I I -shaped core, of which the 


70 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

two outer projections carry potential coils, and the inner the series 
winding. The magnetic circuit is partially closed by a laminated iron 
bridge piece near the top of the three poles, and the aluminum disk 
revolves above the poles. A copper ring may be moved so as to give 
the lag adjustment. These meters are made for single-phase and 
for balanced three-phase circuits with one motor element and one 
disk; for these types the weight of the moving element is 32 grams, 
and the full-load torque is 60, 70, or 80 millimeter-grams, for 110, 
220, and 440-volt meters, respectively; the corresponding losses in 
the potential circuit are 1, 1.4, and 2.4 watts, respectively. The full¬ 
load loss in the series coil is from 2 to 5.7 watts for current ranges 
of 5 to 100 amperes. The polyphase meter for unbalanced loads has 
two motor elements and two disks; the weight of the moving system 
is 75 grams, the torque is 120, 130, and 140 millimeter-grams, for 110, 
220, and 440-volt meters; potential-coil and series-coil losses per 
system are the same as given above for single-phase meters. Three- 
phase four-wire meters have two motor elements, each having two 
series windings. If the neutral conductor is grounded, conductor 
No. 1 is taken through one series winding on one motor element; con¬ 
ductor No. 2 similarly through one series winding on the other motor 
element, while conductor No. 3 is taken through the remaining two 
series windings in succession. If the neutral winding is insulated, 
at least back of the meter, each of the four conductors is taken 
through a series winding. 

ELECTRIC METERS RECORDING TIME ONLY. 

The “ time meter ” for electric circuits as used to some extent 
abroad is practically unknown in the United States. As made by 
the Allgemeine Co., this meter consists of a hand-wound 13-day 
clockwork, with a cyclometer dial reading up to 999 hours. A small 
lever arrests the motion of the balance wheel when no current is 
flowing. When current flows, an electromagnet withdraws the lever 
and allows the clock to run. The electromagnet may be in series 
with the current, or in parallel; in the latter case the main switch 
for controlling the load must be in front of the time meter. A form 
without electromagnet has a single-pole switch built in the meter 
for controlling the load. The closing of the switch mechanically 
releases the clockwork. Another type of time meter is made for 
street-car service, for recording the number of hours’ use of the cur¬ 
rent, as a check on the motorman. As the readings are generally 
taken several times during each trip, a dial for reading minutes is 
also provided. 

An interesting form of time meter is made for determining the 
number of hours’ use of such constant-current devices as laundry 
irons, electric heaters, etc., as a basis for giving a discount from the 
total bill for lighting and heating, as shown by the usual supply 
meter on the whole installation. The release of the clockwork in 
this “ reimbursement meter ” is made by the expansion of a wire 
which is heated by the current. Connections to the meter are made 
by plug contacts, so that the meter may be readily inserted in series 
with the heating device. The weight of this meter is 1 pound 5 
ounces; diameter, 3 inches; and list price, $4.28. It is made in 1, 3, 
5, 7.5, and 10 ampere sizes. The winding of the clock is done by 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 71 


the consumer, it being to his interest to keep going a meter which 
secures him a substantial discount on part of his bill. 

TWO-RATE AND MAXIMUM-DEMAND METERS. 

A. E. G. tw T 0-rate meters are made in two forms. The first has 
an electromagnetic device for coupling the meter spindle to one or 
the other of the two registers, and the change-over is effected by a 
separate pendulum clock, either hand or electrically wound. The 
other form has the clock built in the meter, and the change-over 
is effected mechanically. The maximum-demand meter has a train 
of gears that is connected to the meter spindle at intervals either 
by a separate clock or by a built-in clock. The gearing moves an 
index around the maximum-demand dial. When the clock releases 
the gearing the carrier which has been pushing the index returns 
to its initial position, leaving the index at the highest point reached. 

FUSSNER UND FORDERMAM. 

The firm of Fussner und Fordermann is located in Godesburg, a 
suburb of Bonn on the Rhine. It acquired the electrical-instrument 
business of the Elektrische und Magnetische Apparatebau Gesell- 
schaft, whose product now consists mainly of switchboards and con¬ 
trol apparatus. 

Switchboard and portable instruments are made in moving-coil, 
moving-iron, dynamometer, and hot-wire types. In addition to the 
usual form of moving-coil system, the Schortau system is used for 
switchboard instruments. In this construction a radially wound 
aluminum disk moves in the single air gap of a permanent magnet. 
The disk acts as coil support and damping frame. The list prices 
of instruments with this system are slightly lower than those of 
instruments otherwise the same, but having the usual construction. 

The standard construction of this firm’s moving-iron switchboard 
instruments includes gravity control, spring control being listed as 
an extra. Air damping is used. The firm uses air damping in hot¬ 
wire instruments also, the reason given being that the usual damping 
magnet is sometimes objectionable because of the effect of its stray 
field on neighboring apparatus. 

Other electrical instruments made by this firm include small watch- 
form voltmeters and ammeters, both moving-coil and moving-iron 
types, portable insulation testers, and demonstration instruments. 

S. GUGGENHEIMER. 

The works of Dr. S. Guggenheimer at Nuremberg produce a large 
i line of switchboard and portable instruments. Moving-iron instru¬ 
ments, for example, are made in eight sizes, ranging from 80 to 550 
millimeters (3 to 22 inches) in diameter, in addition to sector and 
profile forms. All are air damped except the 80-millimeter instru¬ 
ments. Mr. Guggenheimer considers that by using suitable die 
castings the cost of air-damped instruments can be kept practically 
as low as that of undamped instruments, and that there is no reason 
for the existence of the latter. Gravity control is standard, spring 
control being supplied on order at an extra cost. 


72 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

Direct-current moving-coil instruments have the pole pieces held 
in position by casting nonmagnetic alloy around them. The stand¬ 
ard ammeter-shunt drop is 60 millivolts, the indications of the in¬ 
strument being said to be independent of temperature. When tem¬ 
perature errors can be tolerated, and the current to be measured is 
large, the drop can be made as low as 15 millivolts. 

Hot-wire instruments have air damping, the presence of damping 
magnets being objectionable in some cases. The “precision milli- 
voltmeter for direct and alternating current ” is a thermal instru¬ 
ment, having a permanent-magnet moving-coil system. The terminals 
of the coil are connected to two opposite corners of a Wheatstone 
bridge made up of four thermocouples. The voltage to be measured, 
either direct or alternating, is applied to the other two corners of 
the bridge. The bridge is so balanced that the line current can not 
enter the moving-coil circuit, nor can the thermal currents pass out 
to the line. An adjustable rheostat marked in temperature degrees 
is used to correct for room temperature changes. The full reading 
requires 225 millivolts at the instrument terminals, and a current of 
1 ampere. For higher current ranges, up to 2,000 amperes, external 
shunts are used. 

Two types of switchboard wattmeters are made, one of which is 
astatic, having two pairs of fixed coils and two mechanically con¬ 
nected moving coils. These instruments are thus unaffected by 
uniform stray fields, and do not require reversal of the current when 
checking by direct-current standards. The same construction is used 
in the portable voltmeters and wattmeters on the dynamometer 
principle. Portable wattmeters with two or three current ranges 
have a knob which is turned to change the range; the maximum cur¬ 
rent and the multiplying constant appear in window openings in 
the scale plate as the knob is turned. 

The “universal measuring instrument for direct and alternating 
currents” is designed to make all practical electrical measurements. 
It consists of an astatic dynamometer wattmeter, a voltmeter, and an 
ammeter, built into a single case. In the lid of the case may be 
fitted a frequency meter of the vibrating-reed type and a slide-wire 
bridge. The instruments are of the profile (edgewise) pattern, with 
scales nearly 7 inches long. 

Registering instruments for direct current have two strong per¬ 
manent-magnet moving-coil systems, each carrying a very light 
grooved aluminum pulley. A fine wire runs over the two pulleys 
and draws the pen in a straight line across the paper. In a similar 
way, the registering wattmeter for polyphase use has two systems 
coupled in the same way, the torques of the two being thus mechani¬ 
cally added. 

HARTMANN & BRAUN A. G. 

The works of Hartmann & Braun A. G. are located in Frankfort 
on the Main. The company was formed in 1884 for the manufacture 
of electrical instruments, which form the larger part of the output 
at tha present time. 

EQUIPMENT AND METHODS. 

The work is carried on in a number of large brick buildings several 
stories high. Most of the machines and tools are of German make, 
although some Brown & Sharpe and Cincinnati milling machines 


[CAL INSTRUMENTS AND METERS IN EUROPE. 73 

are in use. Electrical power is bought, and the machines are driven 
by line and counter shafting, the line shaft in each room being driven 
by a direct-current motor. The procedure in one of the buildings, 
taken as an example, is as follows: Rough castings are received on 
the ground floor and the rough edges and projections are ground off. 
They are then sent up to the floor above to be turned, drilled, etc., 
and then to the next floor to be enameled, plated, or otherwise finished. 
The arrangement of the machines and the method of carrying on the 
work are orderly and systematic, and the welfare of the workmen has 
been considered. For example, dust-producing machines, for grind- 
ing, buffing, etc., are fitted with exhaust connections to prevent dust in 
the workrooms. 

The governing idea in the manufacture seems to be to make the 
best possible jigs and tools, even at high cost, in order to save time 
subsequently in the production and to secure the best possible product. 
As an instance, the scales of precision instruments are drawn on very 
accurate circular dividing engines. These scales are very good, the 
lines being fine and uniform. Many ingenious methods are in use, 
some of which for business reasons can not be described here. The 
following process, however, may be given as an illustration: 

CONSTRUCTION OF MOVING COILS. 

Moving coils are made, as a rule, of aluminum wire, to reduce the 
wear on pivots and jewels and to reduce the moment of inertia. A 
very interesting process is used in the construction of millivoltmeter 
coils. Such coils have sometimes been wound with square or rec¬ 
tangular w T ire, which has electrical advantages for this case. How¬ 
ever, such wires are much more troublesome to wind, and it is not 
easy to make the wire lie close to the frame. Hartmann & Braun 
wind round silk-covered aluminum wire on the aluminum frame, and 
then put the coil in a press which flattens the wire. The pressure is 
so great that the wires are slightly embedded in the aluminum frame; 
nevertheless the insulation between the separate turns and between 
the wire and the frame remains intact. In single-layer coils the cross 
section of the wire after pressing is nearly square; in two-layer coils 
the section becomes approximately an isosceles triangle, the bases m 
one layer being next to the frame, in the other away from the frame. 
This patented construction gives a highly efficient coil. All direct- 
current instruments have the two spiral springs at the upper end of 
the coil. 

LABOR-WELFARE WORK. 

About 550 employees are engaged in the work, of whom less than 
10 per cent are girls. The latter are engaged chiefly in winding coils. 
The officials, engineering staff, and clerical force number about 250, 
making a total personnel of 800. The working day for shop em¬ 
ployees is 9-hours, except Saturday; 53 hours constitute a week’s 
work. The office force, engineering staff, etc., have a somewhat 
shorter day. A notable difference between American and German 
customs is seen in the length of the “ noon hour,” which in Hartmann 
& Braun’s works is from 12 to 2. Most of the mechanical work is 
paid for on a piecework basis. The average instrument maker earns 
about 7 marks ($1.67) per day. 


74 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

Strikes and similar difficulties with the workmen are said to be 
practically unknown. The firm has carefully considered the welfare 
of its workmen. A well-equipped machine shop, under a capable 
instructor, trains apprentices to do accurate work. A small library 
is available to the apprentices. Bathrooms are provided, available 
for a nominal fee. A “ first-aid ” room is equipped with surgical in¬ 
struments, bandaging material, etc., ready to deal with accidents such 
as can not be entirely avoided. By way of preventing accidents, 
shields and warning notices are used. Dangerous parts of machines, 
such as the back gears of lathes, are painted red to remind the user. 
A cabinet in which insulation tests of instruments up to 200,000 volts 
are carried out is made safe by interlocking the door of the cabinet 
and the switch in the low-voltage primary circuit of the transformer. 
The circuit can not be closed until the door is closed. 

The apparatus manufactured includes ammeters, voltmeters, watt- 1 
meters, and other indicating instruments in switchboard and portable 
forms, as well as a large variety of electrical apparatus for scientific 
purposes. Space is not available to enumerate all the types, but some 
particular ones of special interest will be briefly described. 

THREAD POINTER-MULTIPLEX INSTRUMENTS. 

Precision portable direct-current voltmeters and millivoltmeters 
are equipped with a novel form of index called the u thread pointer.” 
A fine stretched wire replaces the usual knife edge, and a small trans¬ 
lucent screen is carried by the pointer. The image of this screen in 
the scale mirror gives a bright background against which the black¬ 
ened wire and its image are clearly seen. It is claimed that this form 
of pointer enables one to make more accurate readings and is less 
fatiguing than the usual form. 

In addition to the usual form of precision millivoltmeter and shunt, 
Hartmann & Braun make duplex, triplex, and quadruplex millivolt- 
meters and shunts in order to supply the need for a large number of 
ranges with the minimum amount of apparatus. A “ multiplex” 
millivoltmeter has several ranges—for example, 30, 60, 150, and 300 
millivolts—all of which are compensated for temperature. A multi¬ 
plex shunt does not differ in principle from the usual form; it is de¬ 
signed to carry the current which gives the maximum drop of poten¬ 
tial required by the millivoltmeter for full deflection—300 millivolts 
in the example above given. This shunt thus serves for as many 
current ranges as the millivoltmeter has potential ranges. In changing 
from one range to another, with a given shunt, the main current is not 
disturbed, as only the potential cable needs to be shifted. Thus the 
readings may be kept well up on the scale at all times. By a special 
arrangement of circuits of different temperature coefficients the multi¬ 
plex millivoltmeters are compensated for temperature on all ranges of 
60 millivolts and higher. The care which is taken in this matter may 
be appreciated from the statement that instead of assuming an aver¬ 
age figure for the temperature coefficient of the copper wire used the 
temperature coefficient of each lot of wire is carefully determined. 

SELF-CONTAINED AMMETERS-SWITCHBOARD INSTRUMENTS. 

Precision portable direct-current ammeters are made with from one 
to four ranges, self-contained, up to 200 amperes. These instruments 
have a common terminal and as many other terminals as the ammeter 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 75 

has ranges. There are no moving contacts in the millivoltmeter cir¬ 
cuit and the one point of contact which is shifted in changing the 
range is in the line, and if it is of variable resistance it can not affect 
the accuracy of the readings. The principle is that of the Ayrton- 
Mather universal galvanometer shunt. It is somewhat surprising that 
many makers have overlooked the advantages of this arrangement, of 
which there is only one instance, a very recent one, on the American 
market. 

A much larger number of styles and sizes of switchboard instru¬ 
ments is made than is the case with American makers. For example, 
seven sizes of round-pattern direct-current ammeters and voltmeters 
are made, ranging from 70 to 530 millimeters (2§ to 21 inches) in 
diameter. Round-pattern moving-iron ammeters and voltmeters are 
made in three sizes, all having air damping. 

HOT-WIRE INSTRUMENTS-USE OF PLATINUM-IRIDIUM. 

Hartmann & Braun were pioneers in the manufacture of hot-wire 
instruments. The first type, invented by Cardew, was of very incon¬ 
venient form; the type introduced by Hartmann & Braun used a 
working wire about 6 inches long and was an improvement over the 
Cardew in other respects. In recent years a radical improvement 
has been made in Hartmann & Braun hot-wire instruments by sub¬ 
stituting platinum-iridium for platinum-silver as the material of the 
working wire. Platinum-iridium can be run at a much greater tem¬ 
perature elevation and its coefficient of expansion is appreciably less 
than that of platinum-silver. As a result, the new instruments are 
much less affected by changes of room temperature and the annoying 
zero shift of the older instruments is greatly reduced. The new in¬ 
struments are made as ammeters and voltmeters, in switchboard and 
portable forms. 

UNSHUNTED AMMETERS FOR WIRELESS TELEGRAPHY. 

An interesting recent development is the unsliunted hot-wire am¬ 
meter for the highest frequencies used in wireless work. Ordinary 
shunted hot-wire ammeters, when used for current at 1,000,000 cycles, 
show very large errors. The new “ hot-strip ” ammeter has a group ol 
thin platinum-iridium strips arranged as elements of a cylinder, the 
ends of the strips being connected to two copper disks, which are 
part of the line terminals. The current passes straight through the 
instrument, avoiding loops, and since the strips are symmetrically 
placed there is no tendency toward change of distribution of the cur¬ 
rent due to change of frequency. The uppermost strip is used as the 
expansion element in place of the usual wire. These ammeters are 
made up to 300 amperes. 

FREQUENCY METERS-HIGH-FREQUENCY GENERATORS. 

Frequency meters on the resonance principle, with vibrating reeds, 
are made in a great variety of forms. For use in connection with 
wireless telegraphy they are now made up to 1,500 cycles per second. 
The resonance principle is also applied to the construction of tacho¬ 
meters, either for direct attachment to the machine for showing 
the speed in revolutions per minute or for operation at a distance 


76 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


by current from a small magneto generator connected to the machine. 
A natural outgrowth of the manufacture of these magneto generators 
is the high-frequency generator, which is made for an output of sev¬ 
eral kilowatts and a maximum frequency of 7,000 cycles per second. 

WIRE FILAMENTS. 


Among the special materials supplied by Hartmann & Braun should 
be mentioned their fine wires (“wire filaments”), which are made 

down to 0.015 millimeter (0.0006 inch) 
in diameter. These are supplied in gold, 
silver, platinum, and other pure metals, 
and also in alloys, a total of 18 materials 
being listed. 

R. KIESEWETTER. 

The works of B. Kiesewetter, of Leip¬ 
zig, produce switchboard and portable 
instruments and accessories. Electro¬ 
magnetic instruments have air damping, 
the patented construction employed be¬ 
ing worthy of special mention. It con¬ 
sists of a sector-shaped box in which 
swings an aluminum vane. A construc¬ 
tion which is employed by some instrument makers is shown in figure 
4. The vane is attached to the shaft by an arm which passes through 



Fig. 4.—Ordinal^ air-damping box. 



Kiesewetter air-damping box. 

the slit a. It is evident that leakage of air through this slit reduces 
the efficiency of the device. To avoid this leakage, Mr. Kiesewetter 
uses the construction shown in figures 5 and 6, the former showing 
the two halves of the box separated to show the interior. The arm 
which carries the vane swings within an extension of the damping 
chamber, and the only place where leakage can occur is around the 
shaft. It is evident that the leakage will be much less than with the 
form shown in figure I. As the box is composed of die castings it is 
not more expensive than the usual form. 




































































ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


77 


POCKET INSTRUMENTS-COIL-WINDING MACHINES. 

A specialty is made of pocket voltmeters, ammeters, and lamp 
testers. In even the cheapest voltmeter, selling for considerably less 
than a dollar, the coil is wound with silk-covered wire, and the scales 
are individually drawn. The voltmeter coils are wound to have the 
same length of wire, not necessarily the same number of turns. By 
this means the resistance is said to be kept more nearly uniform. 
Special winding machines were made for the work, each consisting of 
a head driven by a direct-current motor. A treadle operates a simple 
strap key which makes and breaks the motor circuit. The wire to be 
wound runs once around a grooved pulley, one turn of the wire 
around the pulley being 0.1 meter (3.937 inches) in length. On the 
same spindle with the grooved pulley is a pinion which meshes with 
a gear, giving a 10 to 1 reduction of speed. This gear is on the shaft 
of a revolution counter, and one turn of the shaft, which records 1 
on the lowest dial, corresponds to 1 meter of wire wound. 

The design of the pocket voltmeters is such that no instrument 
takes over 0.1 ampere for full deflection. This is important when 
the voltmeter is to be used for determining the voltage of primary 
batteries having appreciable internal resistance. 

LAND UND SEEKABELWERKE A. G. 

The Land und Seekabelwerke A. G. is located at Nippes, a suburb 
of Cologne; its chief products, as the name indicates, are electrical 
cables of all sorts. It also manufactures electrical instruments, hav¬ 
ing purchased the business originally established at Hanover by 
Dr. K. Franke. 

A complete line of resistance apparatus is made, using manganin 
wire and sheet. A distinctive feature of some of this apparatus, 
including potentiometers, is the use of contact blocks arranged in 
straight lines instead of the usual circles. Other apparatus made by 
this company includes cable-testing sets, fixed and variable induct¬ 
ances, condensers, galvanometers and their accessories, and the 
Franke curve tracer. 

The line of direct-current apparatus includes moving-coil instru¬ 
ments in two constructions. The older construction, due to Dr. 
Franke, has a circular coil moving in spherically recessed pole pieces, 
with a spherical inner core. The pole pieces are threaded and screwed 
into a brass casting which also carries the inner core and forms the 
bearings for the moving coil, thus giving a very solid construction. 
This form is used for switchboard instruments and for moderate- 
priced portables. For the best-grade portable instruments the rec¬ 
tangular coil, as used by nearly all makers, is employed. These latter 
instruments have a feature intended to facilitate accurate reading. 
The usual mirror is used to prevent parallax, and a frosted band, in 
the form of a circle arc, is etched on the cover glass. In use this 
band appears in the mirror as a bright background against which 
the image of the needle appears. Moving-iron instruments are also 
made, in switchboard and portable forms, air damping being used. 

SIEMENS & HALSKE A. G. 

The firm of Siemens & Halske A. G., of Berlin, claims tile distinc¬ 
tion of being the oldest electrotechnical firm in the world, having 


78 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

developed from a small business started in 1847. The products of 
the various factories of this firm and its associated companies cover 
the whole field of electrical engineering. The present description is 
limited to electrical measuring instruments, which form a part of 
the output of the large factory called the Wemerwerk, in Nonnen- 
damm, a suburb of Berlin. The processes of manufacture are thor¬ 
oughly organized. The raw materials are machined in large quanti¬ 
ties into standard parts, which are stored, and are drawn upon as t 
required for assembly. 

MOVING-IRON AND MOVING-COIL INSTRUMENTS. 

Moving-iron switchboard ammeters and voltmeters are made on the 
solenoid and plunger principle, in contrast to the more generally used 
repulsion principle. A disk of specially treated soft iron is caused 
to rotate so as to enter a flattened solenoid, when current flows 
through the latter. The smallest of these instruments, with base 185 
millimeters (5.3 inches) in diameter, has air damping, and in ordi¬ 
nary ranges lists at about 20 marks ($4.76). By the use of pressed 
sheet-iron bases the weight is kept low (1^ pounds). In spite of the 
low price these instruments are well finished and have individually 
drawn scales. By varying the relative position of the iron disk and 
its solenoid for the zero position, the character of the scale of the 
voltmeter is made quite different from that of the ammeter. The 
graduation of the voltmeter scale is open near the working point, 
about two-thirds of the maximum voltage, and is crowded below one- 
half of the maximum. The ammeter scale is designed to be as nearly 
uniform as possible. 

Shunts for moving-coil direct-current switchboard ammeters for 
currents of several hundred amperes and above have rods of resist¬ 
ance material instead of strips. Round pattern moving-coil instru¬ 
ments are made up to a diameter of 690 millimeters (27 inches/. 

SWITCHBOARD WATTMETERS-SHUNTED DIRECT-CURRENT WATTMETER. 

Switchboard wattmeters are made on the dynamometer principle 
and also on the induction (“ Ferraris ”) principle. In addition, a 
special direct-current wattmeter is constructed with an electromag¬ 
net excited by a voltage winding; a moving coil swings in the air gap, 
as in a permanent-magnet moving-coil ammeter or voltmeter. This 
coil is connected to the terminals of a current shunt having a full¬ 
load drop of 60 millivolts. The advantage of this construction is the 
strong torque, namely, 10 millimeter-grams. Because of the strong 
field in which the coil moves, external stray fields exert a relatively 
small influence on the readings. It is stated that the hysteresis error 
resulting from variations of 20 per cent above and below normal 
voltage does not exceed 0.4 per cent. The error following a tem¬ 
porary interruption of the circuit is said to be 0.8 per cent. 

INDUCTION INSTRUMENTS-INSTRUMENT TRANSFORMERS. 

The induction principle is used in the construction of ammeters 
and voltmeters for switchboard use at a definite frequency. The 
switchboard frequency meters are made on the vibrating-reed prin¬ 
ciple. 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 79 

As accessory apparatus for the preceding, current transformers are 
made in ranges up to 30,000 amperes; for currents up to 500 amperes, 
current transformers are made for operation on circuits up to 80,000 
volts. The variety of styles and sizes is very great. Potential 
transformers are made in similar variety up to 80,000 volts. 

PORTABLE AND LABORATORY DIRECT-CURRENT INSTRUMENTS. 

The preceding principles are also applied to the construction of 
portable and laboratory instruments. In the line of permanent- 
magnet moving-coil instruments one type calls for special mention. 
By the use of an aluminum wire coil of small radius a system is made 
which has such good electrical properties that it may be made up as 
a combined millivoltmeter and voltmeter and still give good results 
for either use. As a rule, such combination instruments have a rela¬ 
tively low resistance per volt when used as voltmeters and a rela¬ 
tively high drop when used as ammeters. In the present case, when 
the instrument is used as a voltmeter, the resistance is 333^ ohms per 
volt, or about three times as high as that of the usual portable volt¬ 
meter. When used as a millivoltmeter, the drop for full deflection 
is 45 millivolts, with an internal resistance of 10 ohms; the instrument 
is compensated for room temperature changes for either use. This 
low millivolt drop considerably reduces the size, weight, and cost of 
the shunts. The latter are made exclusively of manganin. The same 
instrument system forms part of a “ technical potentiometer arrange¬ 
ment,” which has an arrangement of circuits by which the moving- 
coil instrument may be checked at one point by reference to a stand¬ 
ard cell. By means of a magnetic shunt, any necessary correction 
may be made for the effect of stray field or other source of error, so 
that the reading at the check point of the scale is correct at the given 
time and place. The instrument will then read correctly at the given 
time and place, within the limit of accuracy of the graduation of the 
scale, so long as the disturbing influences remain constant. This 
apparatus is especially designed as a standard instrument for those 
cases where a potentiometer is inadvisable. It is arranged to meas¬ 
ure voltage in several ranges, and also current, with suitable shunts. 

ELECTRODYNAMOMETER INSTRUMENTS. 

In addition to a “ laboratory type ” of dynamometer ammeter, 
voltmeter, and wattmeter, which has been made for a number of years, 
a new model has been brought out recently. These instruments have 
metal cases, and are smaller and lighter than the laboratory type; 
they are intended for use in practical testing, especially in connec¬ 
tion with current and potential transformers. The wattmeter and 
ammeter of this type are made in 5-ampere range only. 

Several types of dynamometer wattmeter are made for special uses. 
One type resembles in outside appearance the direct-current portable 
instrument, but has a tube covering the strip suspension of the moving 
coil. This suspension greatly increases the sensitiveness, so that full 
deflection requires only 1.2 watts. A similar instrument with a 
shunted current coil gives full deflection for 6 watts : and is especially 
intended for measuring the power lost in the potential circuits of 
alternating-current meters. For measuring power at very low power 


80 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

factors a large astatic wattmeter with strip suspens n . made in 
several ranges. These will give full deflection for p< < dp-tors as 
low as 2 per cent, and are intended for measuring the losses ibles 
and in inductance coils. Such a wattmeter with a 1-ampere current 
range gives full deflection for 0.0015 watt. 

A line of portable instruments is made for work not requiring the 
highest accuracy. The systems employed are substantially those used 
in round-pattern switchboard instruments, parallax mirrors not being 
supplied. These instruments are made on the moving-coil, moving- 
iron, and induction principles. The vibrating-reed principle is also 
used in portable frequency meters. 

CURRENT TRANSFORMERS-GALVANOMETERS. 

Current transformers for use with portable and laboratory instru- 
menfs have iron cores of liberal cross section without joint. The 
figures given for ratio and phase angle of these precision transformers 
are very good and justify the extra trouble and expense of the con¬ 
struction used, when the transformers are to be used on accurate 
work. 

Moving-coil galvanometers are made in a variety of forms, from a 
simple portable to a sensitive reflecting instrument. This company 
is to be commended for stating in its catalogue all necessary data in 
regard to its reflecting moving-coil galvanometers, namely, coil re¬ 
sistance, total resistance for critical damping, period, and sensitivity. 
No other maker states all four, to the writer’s knowledge. 

RESISTANCE APPARATUS-POTENTIOMETERS. 

Resistance standards, boxes, etc., are made after the Reichsanstalt 
models, using manganin for all but very high resistances, where 
constantan is superior. Potentiometers are made in two forms— 
the Raps and the new Feussner. Apparatus is made for testing the 
magnetic properties of iron, for the shop and field testing of resist¬ 
ance and insulation, and for the measurement of inductance. * The 
Siemens-Blondel oscillograph is of the type employing a fine wire 
loop stretched in the field of an electromagnet and carrying a light 
mirror. 

SIEMENS - S CHUCKERT WERKE. 

The Siemens-Schuckert Werke at Nuremberg construct dynamos, 
motors, and other electrical equipment, including electric meters, of 
which the company is one of the largest makers in the world. The 
daily production exceeds 1,000 meters. 

DIRECT-CURRENT WATT-HOUR METERS. 

The G5 direct-current watt-hour meter has circular field coils and 
a spherical armature having three coils 120° apart, connected as a 
drum winding. The three-part commutator is not soldered to the 
armature leads, but the connection is made by three plated steel 
springs. Damaged or worn commutators can thus be quickly re¬ 
placed and afterwards repaired at the station. The brushes are of 
silver strip, faced with gold wire where they touch the commutator. 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 81 

and may be readily removed and replaced without altering the ten¬ 
sion. The armature shaft is tapered at the bottom and has a re¬ 
newable steel pivot. The removal of the jewel screw also removes 
the pivot. Oil is used in the bearing, which is constructed so as to 
retain the oil while the meter is being transported. An iron plate 
is used to screen the drag magnets from the stray field of the series 
coils. The series resistance is wound on porcelain spools. Cyclom¬ 
eter dials are standard, the ordinary pointer dial being supplied 
only on special order. The number wheels are advanced suddenly by 
the falling of a weight raised by the spindle of the lowest wheel. 
The torque of the G5 meter is given as 85 millimeter-grams. 

AMPERE-HOUR METERS. 

The A2 meter is a direct-current ampere-hour meter, having a flat 
disk armature with three coils revolving between strong permanent 
magnets, which furnish the driving and braking field. The arma¬ 
ture resistance is about 33 ohms, so that small changes of brush con¬ 
tact resistance cause no appreciable errors. The shaft is fitted with 
a removable pivot which comes away with the jewel screw when the 
latter is removed. Oil is used in the jewel bearing. The full-load 
speed is about 100 revolutions per minute, and the torque about 90 
millimeter-grams. The current to be measured flows through a shunt 
contained in the meter, around which the armature circuit is con¬ 
nected. The drop of potential at full load is about 1.5 volts. 

INDUCTION WATT-HOUR METERS. 

The W10 meter is a compact low-priced meter for alternating cur¬ 
rents. In general appearance it resembles the small round meters 
brought out in the last few years in the United States. The diameter 
of the case is about 6 inches and the weight 7 pounds. The following 
figures are given for the W10 meter: Full-load torque, 55 millimeter- 
grams; weight of moving element, 30 grams; full-load loss in series 
coil, 2 watts; shunt loss, 1 watt. This meter is furnished only with 
cyclometer dials. 

The W2 meter for alternating currents is a larger form than the 
preceding and has a special feature for improving the light-load ac¬ 
curacy. The lower bearing is supported on a flat spring, which car¬ 
ries a small iron armature. An electromagnet near the armature is 
connected in the potential circuit and vibrates the lower bearing, 
reducing the friction. Up to 50 amperes the weight of this meter is 
13 pounds; above 50 up to 300 amperes, 20 pounds. The following 
data are given for the W2 meter: Full-load torque, 75 millimeter- 
grams; w T eight of moving element, 40 grams; full-load loss in series 
coil, 3 watts; shunt loss, 1.2 watts. 

The D5 meter for three-phase four-wire circuits has two disks on 
one shaft. Two motor elements act on the lower disk and one motor 
element and the two drag magnets on the upper disk. 

The D6 polyphase meter has two disks on one shaft; the lower is 
acted on by one motor element and the upper by the other element and 
the two drag magnets. The following figures relate to the D6 meter: 
Full-load torque, 110 millimeter-grams; weight of moving element, 
65509°—13 - 6 


82 ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 

80 grams; full-load loss in each series coil, 2 watts; loss in each po¬ 
tential coil, 1 watt. 

SUBTRACTION ARRANGEMENT FOR WATT-HOUR METERS. 

All types of Siemens-Schuckert meters may be fitted with a “ sub¬ 
traction arrangement.” This is intended to record all use of current 
in excess of a specified load for which a contract rate is paid. The 
arrangement consists of a differential gearing, one side of which is 
driven by a clock at a constant speed, depending on the amount of the 
specified load. The other side is driven from the worm on the meter 
spindle, which also drives a register showing the total current used. 
The planet wheel of the differential gearing drives a second register 
only when the speed of the meter spindle exceeds the speed corre¬ 
sponding to the specified load. A ratchet wheel and pawl allow the 
second register to run forward only. This type of meter is termed a 
“ depassement ” meter by French makers. 

MAXIMUM-DEMAND METER. 

The polyphase meter with maximum-demand arrangement contains 
a clockwork driven by a small induction motor, the rate being con¬ 
trolled by a balance wheel. A train of gearing is driven from the 
meter spindle and is arranged to rotate a gear wheel having a pro¬ 
jecting pin which drives the maximum-demand index forward over a 
scale. At intervals, say every 15 minutes, the clockwork releases 
this gear wheel and a spring returns the wheel to its initial position. 
The index remains by friction in the highest position reached until 
set back by hand; the scale is marked to read the maximum demand. 

VEREINIGTE ELEKTROTECH1VISCHE INSTITUTE. 

The Vereinigte Elektrotechnische Institute (Yeifa Werke) is lo¬ 
cated in Frankfort on the Main. In addition to a large output of 
electromedical apparatus, including X-ray apparatus, a line of 
switchboard and portable electric instruments is made. 

Moving-iron instruments are all made with spring control, and 
all sizes from 130 millimeters (5 inches) diameter up have damp¬ 
ing. The 5-inch instrument has damping of a novel form. Two 
damping vanes 180° apart move in the annular space between the 
cylindrical case and a cylindrical inclosure around the solenoid. 
This makes a special damping box unnecessary. In spite of 
the low price of these 5-inch instruments—$3.84 to $5.76—the scales 
are individually made on circular dividing machines. The 200- 
millimeter (8-inch) moving-iron instrument has oil damping. 
Permanent-magnet moving-coil instruments are made with the usual 
form of magnetic system and coil, for currents up to 1,000 amperes. 

Hot-wire instruments supplied by the Veifa Werke have a device 
which short-circuits the working wire at a predetermined overload, 
to protect it from damage. Ammeters for direct connection in high- 
voltage circuits (up to 12,000 volts) are mounted on porcelain in¬ 
sulators tested to 50,000 volts. Other products include watch-form 
ammeters, voltmeters, and lamp-testing instruments, as well as mil- 
liammeters designed for electromedical work. 


ITALY. 

C. G. S. ELECTRICAL INSTRUMENT CO. 

The C. Gr. S. Electrical Instrument Co. (formerly C. Olivetti & Co., 
of Ivrea) is located at Via Broggi No. 4, Milan. It occupies a three- 
storv stone building, on the first floor of which are the departments 
for machine work, die casting, and plating. The second floor is oc¬ 
cupied by the winding and assembly departments, and also by the 
calibrating and testing laboratories. The third floor contains the 
offices. 

EQUIPMENT AND METHODS. 

Nearly all the machine tools are of American make, including 
Brown & Sharpe milling machines, Reed lathes, Prentice lathes, 
Pratt & Whitney lathes and drills, Norton grinding machines, Bliss 
presses, Gould & Eberhardt shapers, and Cincinnati milling ma¬ 
chines. The high quality of American tools is fully appreciated by 
this firm. 

The American system of interchangeable parts is used in all 
Olivetti instruments. The tolerance allowed on general wprk is plus 
or minus 0.02 millimeter (0.0008 inch) ; for some parts the limits are 
still closer. The company has developed a die-casting process which 
greatly reduces the work required on many of the instrument parts; 
it is said that the castings frequently come out more accurate than 
the limit of tolerance above mentioned. All Olivetti instruments 
are damped; for all types of indicating ipstruments except the mov¬ 
ing-coil permanent-magnet type, this is accomplished by an air¬ 
damping box. The use of die castings is of especial advantage at 
this point, and enables the production of a damped instrument at a 
moderate price. 

OUTLINE OF PRODUCTS-RECORDING INSTRUMENTS. 

The product of the company consists of indicating and recording 
electrical instruments and instrument transformers. Round-pattern 
switchboard instruments are made of 15, 16, 18, 20, 22, 80, 41, and 60 
centimeters (6 to 24 inches) diameter, to meet the various demands 
of home and foreign trade. Voltmeters, ammeters, and wattmeters 
are included, of electromagnetic, moving-coil, permanent-magnet, 
electrodynamometer and hot-wire types. An important part of this 
company’s product, by which it is perhaps best known, is its large 
variety of recording instruments. These are made in round pattern 
(85 centimeters diameter) with hot-wire movement; in rectangular 
form (two sizes) of hot-wire, electromagnetic, and moving-coil types, 
and a large rectangular pattern operating on the relay principle, 
which is furnished Avith moving-coil or with electrodynamometer 

83 


84 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


movement. Potential transformers are made up to 80,000 volts, and 
current transformers are regularly supplied up to 6,000 amperes; 
on order, they are made up to 30,000 amperes. 

SUMMATION WATTMETERS-PORTABLE INSTRUMENTS. 

An interesting type of instrument which seems to be made only by 
this company is the “summation” indicating (or recording) watt¬ 
meter, which enables the total power of a number of alternators to be 
indicated on a single dial or recorded on a single chart. A recording 
wattmeter of this type is in operation in Milan, which traces on a 
single chart a record of the combined output of 19 alternators. 

Portable instruments are made in two grades, namely, a “ portable ” 
at a moderate price for commercial use, where an accuracy of 1.5 per 
cent is sufficient, and a “ control ” instrument for use in laboratory 
work, where a higher accuracy (0.5 to 0.7 per cent) is desired. These 
two grades are made in all the types specified above for switchboard 
instruments. 

Indicating instruments also are made on the relay principle for 
switchboard use and (in a different form) for laboratory work. An¬ 
other useful instrument supplied by the Olivetti Co. is the rolling 
planimeter, which enables the diagrams drawn by their rectangular 
recording instruments to be rapidly integrated. At a single opera¬ 
tion a length of chart of 3 to 4 meters (or longer, if a longer table 
is used) can be integrated, and the construction is such that the result 
may be read in kilowatt hours for recording wattmeters of all ranges. 

LABOR CONDITIONS. 

The company’s force numbers about 150 employees; the Avorking 
day consists of 8 hours for the engineering and clerical staff, and 10 
hours for the workmen. Girls are employed for some of the winding 
operations, and the more delicate work of assembly; they also assist 
in some of the testing work and in the drawing of instrument scales. 
The average wages are as follows: First-grade mechanics, a minimum 
of 8 francs ($1.54) a day, with opportunity to earn, say, 9 francs 
($1.74) by exceeding a certain limit of work accomplished; second- 
grade mechanics, 4 to 5 francs ($0.77 to $0.97) a day under a similar 
arrangement ; the minimum for male employees is 3 francs ($0.58) 
for boys; girls earn from 2 to 3 francs ($0.37 to $0.58) per day. The 
company is in position to select its employees, and has no trouble due 
to disaffection on their part. The company has never had a strike. 
The cost of living is high in Milan, being not far beloAV that of Paris. 
In the last year or two wages have been increased by the company 
about 25 per cent, and the prospect is that further increases will be 
required. 

SOURCES OF MATERIALS-MARKETS. 

The company draws -its supply of raw materials from various 
sources. Insulated wire, copper, and porcelain parts are bought from 
Italian sources; other insulating materials principally from Germany 
or France. • Sheet steel is bought from England, in spite of the higher 
cost as compared with German steel. The company considers the 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 85 

English steel of higher quality for its purposes. Instrument jewels 
are bought in Italy, where the business of cutting jewels is said to be 
very extensive; sapphire, garnet, and agate being imported in the 
rough and exported as finished jewels to England, Germany, Switzer¬ 
land, and France for use in watches and electrical instruments. The 
principal source of supply of the raw material is said to be Australia ; 
American electrical instrument makers, however, usually refer to 
Ceylon as the source of the sapphire they use. 

The duty on English steel sheets imported into Italy is stated to 
be 15 to 17 francs ($2.90 to $3.28) per 100 kilos (220.6 pounds). The 
company is aware of the good quality of American steel, but has had 
no offers from American makers, who maintain no stock in Italy. 
In general, the makers of dynamos, motors, and transformers in Italy 
are said to obtain their steel from German firms who maintain branch 
houses in Italy with large stocks. The company has obtained insulat¬ 
ing varnish and transformer oil from America, but has found it diffi¬ 
cult to buy these American materials because there is no agent in 
Italy and no stock is carried. The company states that the diffi¬ 
culties in the way of buying directly from American makers are: (1) 
The distance; (2) American makers desire to sell catalogue (stand¬ 
ard) material only, and do not take the time and trouble to study 
the special needs of foreign customers. They consider it very im¬ 
portant for American firms who wish to sell goods to Italian con¬ 
sumers to quote “ franco” (free) in Italy. German firms will quote 
f. o. b. customer’s works if requested. In general, American firms 
should quote “franco vagone ” (free on cars) at the customer’s ship¬ 
ping address, with freight and duty paid. 

The company has tried French and German magnets, but has found 
the quality to be less satisfactory than that of magnets made in its 
own shops, and it is therefore now making all of its magnets. The 
most satisfactory steel is obtained from England. American makers 
of magnet steel maintain no stock in Italy, and have no agents, so far 
as the company is aware. The company’s product is sold largely in 
Italy, and a considerable amount is exported to Switzerland, France, 
and Sweden. 

COMPAGNIA ANONIMA CONTINENTALE GIA J. BRUNT & C. 


The Compagnia Anonima Continentale gia J. Brunt & C. was 
founded in 1846 by an American, John Brunt. It makes all kinds of 
apparatus used in the manufacture of gas, including gas meters. 
Other products of the company include water meters, lighting fix¬ 
tures for buildings and for street illumination, and electric meters, 
of which latter about 3,000 to 3,600 are made annually. 

The company’s buildings are located in Milan at 41-43 Via Quad- 
ronna, and are of stone. The equipment for the manufacture of elec¬ 
tric meters was procured almost entirely in Europe; the same is true 
of the materials. The company has made no attempt to secure mate¬ 
rial or equipment from the United States. 

PIECEWORK PLAN, WITH MINIMUM WAGE GUARANTEED. 

The total number of employees varies from 300 to 500, according to 
the conditions of business; of these, about 30 men are now employed 
in the manufacture of electric meters. No women are employed in the 


86 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


factory, but some of the lighter work, such as the winding of coils, is 
sent out to be done at home by women, usually by the wives of 
men employed in the works. The working day is 10 hours ; the mini¬ 
mum daily wage for a skilled man is 6 to T francs ($1.16 to $1.35). 
The employees of each department of the Avorks have a union of their 
OAA T n, but the operation of this union is quite different from that of 
trade-unions in the United States. For example, the men in the foun¬ 
dry are dealt with by the firm as a unit; the castings are paid for on 
the piecework plan, but a certain minimum daily \yage is guaranteed. 
Defective castings are not paid for. The work is figured in large 
lots, and any surplus above the guaranteed minimum is divided 
equally among the men. For example, a lot of castings will be made 
by the men of the foundry and the pay for the lot, on the piece basis, 
is 1,000 francs. The time required is such that the men receive as 
their guaranteed minimum 700 francs. The remainder, 300 francs, 
is divided equally among the men, regardless of their time of service 
Avith the company. This plan has tAvo marked advantages: First, it 
incites the men to do their best work in order to avoid defecth T e cast¬ 
ings for which no pay is received; second, it eliminates shirking, as 
each man is watched by others; a shirker is put out of the factory by 
the workmen themselves. Before this plan Avas put into effect about 
40 per cent of the castings were defective; now only about 2 or 3 per 
cent are defective. 

There are said to be no trade-unions here of the kind known in the 
United States and England, and no strikes. The workmen in each de¬ 
partment of a factory in Milan have a representative in a central body 
which meets to consider requests and discuss matters of interest. All 
the emploA^ees of the Brunt Co. are insured by the firm against acci¬ 
dent, and the men lia\ T e a mutual-benefit fund from which aid is 
given in case of sickness. This fund is maintained by small assess¬ 
ments leA r ied on the Avages; also by fines imposed for tardiness, loss of 
tools, or unwarranted damage to tools or material, and so on. 

The products of the company are in the main absorbed by the home 
demand, though iron castings, fences, gates, etc., have been shipped to 
Buenos Aires; some gas producers have been shipped to Armenia. 
The electric-meter output is sold in Italy. As this branch of the 
business is hardly 10 years old, and as German, French, and Ameri¬ 
can competition must be met in the company’s home market, it has 
not felt justified in attempting to compete in foreign markets. 

SOCIETA ANONYME SIRY, CHAMON & C. 

The Societa Anonyme Siry, Chamon & C., of Milan, manufactures 
gas machinery and other appliances, including gas meters. Fixtures 
for gas and electric light are made in a great variety of designs, 
some of Avhich are very artistic. These fixtures differ in one detail 
of construction from many American designs in that solid castings 
are used for many -parts that in American fixtures would be made of 
stamped or spun sheet metal. 

In addition to the foregoing principal items, the company also 
makes Ayater meters and electric meters. The annual output of elec¬ 
tric meters amounts to from $135,000 to $154,000, the selling price 
per meter ranging from $9.65 to $57.90. 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 87 

The company’s works are located at 95 Via Savonna, in one of the 
manufacturing portions of Milan. The buildings are modern and 
w T ell lighted, with saw-tooth roof construction. 

The company, being a branch of a French concern manufacturing 
electric meters, has found it desirable to procure all the meter parts 
from the Paris factory; thus the work here consists only of assem¬ 
bling and testing new meters and repairing old ones. Two large 
rooms suffice for this work, and 1G men are employed. 

The working day is 10 hours; payment is on the piecework'basis. 
For example, meter testers are paid 30 centesimi (about $0.0G) per 
meter, and at this rate can earn 3 to 5 lire ($0.58 to $0.97) per day. 
Assembly and repair work are done in lots under piecework contracts 
made with the employees by an experienced foreman, who decides 
for each lot what to offer for the work. The methods in use in the 
meter department presented no special features requiring descrip¬ 
tion. One feature of construction of the meters may be mentioned, 
namely, the use of copper disks for all meters. 

The company insures its men against accident, and the men main¬ 
tain a sick-benefit fund. It is stated that no trouble from strikes 
has been experienced. The company sells all its electric-meter output 
in Italy and also sells the other electrical instruments made by the 
Paris house. 

SOCIETA EDISON PER L.A FABBRICAZIONE DI MACCHINE ET APPA- 
RECCHI/ELETTRICI. 

The Societa Edison per la Fabbricazione di Macchine et Appa- 
recchi Elettrici, C. Grimoldi & C., is located at G Via Broggia, Milan. 
It manufactures and deals in dynamos, motors, switches, and other 
materials, and is the sole maker for Italy of the Wright maximum- 
demand meters, for indicating the maximum value of the electric 
current taken by consumers. 

From 2,000 to 3,000 of these are made annually. These meters are 
very simple, and require little manufacturing equipment. The glass 
tube filled with sulphuric acid, which is an essential element, is made 
for the firm by outside glass blowers. The meters are tested in lots 
connected in series, and the readings are taken on a movable milli¬ 
meter scale which is applied to each meter in succession. A curve 
is plotted for each meter and a scale is laid out to fit it. 

The company also makes induction watt-hour meters, the annual 
production being about 500 meters. The company has manufactured 
direct-current watt-hour meters similar to the Thomson in principle, 
but at the present time is making very few of these, as it intends to 
redesign this type. 

ADDITIONAL NOTES. 

An Italian electric railway engineer states that much American 
electric railway material is used in Italy, in spite of its higher cost 
as compared with similar material from other sources. The reason 
for this preference, he says, is that the American material outlasts 
the others and stands more abuse; motormen have found that they 
can throw the current on as rapidly as they choose with American 
motors, while other makes will not* stand such handling. He adds 


88 


ELECTRICAL INSTRUMENTS AND METERS IN EUROPE. 


* 


that the American makers have a good many years’ more experience 
back of them and have learned how to make durable apparatus. 

The Milan Edison Co. has in service about 35,000 meters, of which 
a large number are Ferranti alternating-current induction type and 
Ferranti direct-current mercury t}^pe. They also use some Thomson 
meters of French manufacture. They have tried one of the promi¬ 
nent American meters for alternating current and found it better 
electrically than the Ferranti, but not so capable of standing the 
rough handling that meters are liable to get in transportation to and 
from the premises of consumers. The American meter iii question 
has a pressed sheet-metal case; the Ferranti meters have strong cast- 
iron cases and are quite heavy. In testing the customers’ meters in 
position, they prefer the wattmeter and stop-watch method to the 
use of portable rotating standard watt-hour meters, partly because of 
the troublesome correction curves of the latter. The rotating stand¬ 
ard is used of necessity for motor installations where the load fluc¬ 
tuates rapidly. They test at 10, 20, 50, and 100 per cent of rated 
load. The equipment and methods used in the meter-testing depart¬ 
ment are not appreciably different, in a general way, from those used 
in the larger American stations. A card index of the meters is kept 
in quadruplicate (1) by the maker’s serial number, (2) by the Milan 
Co.’s serial number, (3) by the customer’s name alphabetically, (4) 
by streets. In addition, several colors of cards are used; for example, 
white for light, another color for power, another for “ forfait ” 
system, and so on. The principal data in regard to the meters are 
also kept in books arranged according to the Milan Co.’s serial 
(accession) number. 

The frequency most commonly used in Italy is 42 cycles per sec¬ 
ond ; 40 and 50 cycles are used, though not to a great extent. 

o 


LB Ap ’13 






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